In the Ramayana, we get an introduction to Rama’s qualities, right at the beginning. Valmiki asks Narada who is the gunvaan who has 16 auspicious qualities, and Narada replies that he can think of only one person, namely Rama. In the Vishnu Sahasranama, of the 32 names which praise Rama, the first 16 reveal to us His story, said M.A. Venkatakrishnan in a discourse.
Rama avatara is a poorna avatara. Avataras like Vamana or Narasimha were of a short duration, ending as soon as the purpose of the avatara was fulfilled. But as Rama, He did not end His avatara upon killing Ravana. He stayed on in the Earth for a long time after the killing of Ravana. His decision to be born to Dasaratha and Kausalya was itself due to His kindness. Spending ten months in the cramped space of a mother’s womb was something the Supreme One need not have opted for. But He did it, in order to save people. Throughout the Ramayana, one finds evidence of His superior qualities. That is why Rama avatara is a complete avatara.
Dasaratha wants to crown Rama as Yuvaraja, because he (Dasaratha) is ageing. Kamban has a beautiful description of how Dasaratha notices his old age. He sees himself in the mirror one day, and notices grey hairs near his ears. Kamban says that Ravana’s sins took the form of Dasaratha’s grey hairs! It was on account of his age that Dasaratha is keen to confirm Rama as the next ruler. It is because of this decision that Kaikeyi becomes envious and wants Rama banished. And it is because Rama goes to the forest that Sita is carried off and Ravana is eventually killed. So Kamban sees Dasaratha’s grey hairs as Ravana’s sins! Dasaratha extols Rama’s qualities to the assembly summoned by him when he decides to make Rama the next king.