The story of Ravana, from a paraphrase of the Malay/Indonesian Hikayat Seri Rama, compiled by Shellabear and quoted in Rama Legends and Rama Reliefs in Indonesia:
Maharaja Ravana with his ten heads and twenty arms was sent by his father on a ship to Bukit Serandib, because he had behaved very badly. His father was Citra Baha and his mother Raksa Pandi, the daughter of Dati Kavaca. Reaching Serandib he carried out penance in that island. He hung himself down from a tree with his head downwards.
While Adam was living on earth, he saw him hanging there and was requested by the ascetic to speak for him in front of Allah that he should get four kingdoms. As his penance had been crowned with great success he got married. To begin with he entered into matrimony with the princess from the world of spirits, Nila Utama, who bore him, in due course of time, a son, Indera Jata. This prince had three heads and six arms and he was made the king of the kingdom of spirits at the age of twelve.
After that Ravana married the princess of the earth, Puteri Pertivi Devi, who also bore him a son, called Patala Mahirajan. Even he became a king at the age of twelve, on earth. A third marriage was made with the queen of the seas: Ganga Mahadevi. The son from this marriage was Ganga Mahasuri, who became the king of the seas at the age of twelve.
Thus Maharaja Ravana was the lord of all the worlds from the east to west. There were, however, four kingdoms which were not under his rule. The first was Indera Puri, the second Biruhasya Purva, the third Lagur Katagina, and the fourth Ispaha Boga. But, apart from these, there was everything on and in the earth, in the sea and within air, subject to the kind of reksasas, who had a magnificent palace built for him on the Bukit Serandib: Lanka Puri.
From the Hikayat tradition collected by Roorda van Eysinga, again quoted from the same source:
Dasarata the king of Ispaha Boga, the fourth of the kingdoms independent from Ravana, was the son of Dasarata Cakravati. Raman was the son Dasarata, the son of Nabi Adam.
As Maharaja Dasarata was still childless, after many years he tries to liberate himself from this terrible worry by the advice of a holy man. After consulting the sacred books, his advice was as follows, "Sacrifice for three days in the middle of the field."
Accompanied by one thousand disciples, the holy man flew through the air to the palace city of Mandura Pura and carries out a solemn sacrifice, after he has been solemnly fetched. The sacrificial rice was divided up into six balls. From these three balls were given to (Dasarata's first wife) Mandu Dari, and three to (the second wife) Balia Dari. But suddenly a crow, in actual fact an ancestor of Maharaja Ravana, all of a sudden came there and carried away one of the balls meant for Balia dari. In great rage the holy man cursed the crow and said that it would die by the hand of Mandu Dari's son and further whoever eats this rice ball would get a daughter, who would marry that son. The bird then flew to Lanka Puri, and reported to Ravana what had happened. On hearing this Ravana ate the rice.
After some time Mandu Dari gave birth to a son called Seri Rama, whose body color was emerald green and whose face was a beautiful as the full moon. She gave birth to a second son called Laksemana. Balia Dari gives birth to two sons Berdana and Citradana and after that to a daughter Kikuvi Devi. As Maharaja Dasarata once gets very ill with an abcess in the groin region his life was again saved by Balia Dari who sucked out the pus.
Ravana, on hearing about Mandu Dari, immediately leaves for Mandura Pura, disguised as a brahmin. He comes there to a gate with seven locks which, however, opened by itself on his muttering a magic formula and allows him to enter the palace. In the middle of the front coutryard, he sits down and begins to play his lyre. Dasarata, who was sleeping at Mandu Dari's side, was woken by the music, and as he went to the door, he saw a Brahmin in whom he recognized Ravana.
After a short talk, the latter lets Dasarata know that he wants to take Mandu Dari with him. Dasarata refuses in the beginning because of the children, but then finally promises to give her to him. But his wife is not apparently agreeable to this decision because she goes in her palace and scratches off her skin and makes a ball as big an egg from the skin. She puts this on a golden plate and sacrifices it. As a result the ball changes into a green frog. Even this is brought as a sacrifice and finally turns into a beautiful woman, a replica of Mandu Dari. Ravana goes off in great haste with this pseudo Mandu Dari (she is called Mandu Daki from now onwards, since daki = thrown off skin.) Dasarata who is very surprised to see own wife again, since he has seen his guest going away with her, accepts what has happened temporarily.
... After some time Mandu Daki gave birth to a daughter as beautiful as gold. Ravana sends immediately for his brother Maharaja Bibu Sanam, who comes with his pupils to Lanka Puri because he was a famous magician.
The horoscopes are drawn up but with a shake of his head Bibu Sanam relates that whosoever marries this child would kill its father and rule over the four worlds. Ravana was naturally unhappy at this prophecy and wanted to kill the girl immediately, but the mother suggested that it should be put in an iron box, and thrown into the sea and so it happens. The baby is given the breast for the last time, given over to its enang (governess), who then gives it back to Ravana. He gives the child to Bibu Sanam who throws the casket into the sea.
In the meantime the child in the iron casket floated from Lanka Puri to Darvati Purva to Maharesi Kali. One morning the saint was worshipping the sun. While doing do he stood with his navel in the sea, when the casket hit against his legs. After he had finished his prayers, he took it with him to his wife Manuram Devi. To the surprise of both, the whole house is filled with light as soon as the casket is opened and from the breast of Manuram Devi milk flows. It is clear to them that it has been destined by the gods that they become foster parents of this beautiful girl. Then Maharesi Kali plants forty palm trees in a row and says: "he who can cut through all these forty palm trees with one shot, he should marry this girl who was named Sita Devi."
As Sita Devi is twelve years old kings come from all regions to Maharesi Kali in order to fulfil his wager and to win his daughter as their wife. Even Ravana came in his flying chariot and it was like the heaven falling down. Maharesi Kali, however, missed the sons of Dasarata among the princes and did not wish to give Ravana any chance, before these princes were invited. On the advice of his wife, he went to bring Seri Rama and Laksemana and left for Mandura Pura.
AK Ramanujan asks in his essay Three Hundred Ramayanas: Five Examples and Three Thoughts on Translation:
How many Ramayanas? Three hundred? Three thousand? At the end of some Ramayanas , a question is sometimes asked: How many Ramayanas have there been? ...
In several of the later Ramayanas (such as the AdhyatmaRamayana , 16th C.), when Rama is exiled, he does not want Sita to go with him into the forest. Sita argues with him. At first she uses the usual arguments: she is his wife, she should share his sufferings, exile herself in his exile, and so on. When he still resists the idea, she is furious. She bursts out, "Countless Ramayanas have been composed before this. Do you know of one where Sita doesn't go with Rama to the forest?" That clinches the argument, and she goes with him.
In his essay, Ramanujan compares the story of Ahalya in Valmiki's Ramayana against that in the Ramayana of Kampan. The choice is interesting. The beauty of A-halya (the unploughed) is that of land not yet brought under cultivation. Sita's beauty is that of the furrow in new ploughed land. Rama is green as the new crop. His sons Lav (to scythe) and Kush (spear-grass) have strong connection to the furrow. Ahalya lets a stranger into her home because the stranger has taken on the form of her Brahmin husband - but is actually the god Indra. Sita lets a demon cross the 'Lakhsman rekha' of the hut's threshold because the stranger has taken the shape of a Brahmin sage. Both are punished for being object of a stranger's lust.
During their visit to Java in 1927, Tagore and Suniti Chatterjee encountered the tradition that Rama and Sita were siblings (or at least half-siblings.) Tagore found this interesting, and talked with Dutch orientalists, who confirmed that in their opinion the incest myth was the older one, and that it had been rewritten in the Indian tradition but not in the dispersed ones living on in South East Asia. In a letter home Rabindranath wrote:
If this opinion were to be true, I see some huge congruences between the Ramayana and the Mahabharata. At the root of both the stories are two marriages. Both the marriages are, according to custom, inadmissible. In Buddhist histories we hear of brother-sister marriages but it is completely against our traditions. On the other side, one woman being married to five brothers at once is also novel and non-traditional. The second congruence is the test-of-arms at the first step of each marriage, even as that test is irrelevant to the purpose of each marriage. The third congruence is that neither bride is born from the womb of a woman -- Sita is the Earth's daughter, discovered in a furrow at the tip of the plough, Draupadi (Krishnaa) is created from a Yajna. The fourth congruence is the grooms in each case being subjected to usurpation of their kingdom and banishment to the forests with their wife. The fifth congruence in both stories is the molestation of the wife by the hands of the enemy, and revenge for the molestation.
Suniti Chatterjee, perhaps the greatest comparative-linguist in modern Bengal, was to cause a furore late in his life by claiming that the Ramayana had its origin in the Buddhist tradition, in the Dasaratha Jataka which was older than the Hindu sources. In an extempore lecture at the Asiatic Society, Kolkata, in January 1976, he contended that Rama was the sister of Sita, whom he married. See here for the Jataka, which carries the motif of Rahul's mother being the Buddha's sister.
And tinikidanuphanirayaramayanadakavigalabharadali? By the fourteenth century, there were already so many Ramayanas that Gadhugina Veera Naranappa (the classical Vijayanagara poet, whose nom-de-plume was Kumaravyasa) chose to write a Mahabharata instead, because he had heard the cosmic serpent who upholds the earth groaning under the burden of all the cacophonous Ramayana poets ( tinikidanu-phaniraya-ramayana-daka-vigala-bharadali)!