Vinu
In Valmiki, all 4 brothers RLBS were parts of Vishnu's avatar, as per the payasa that was distributed b/w KSK. It's in Adhyatma Ramayan and its derivatives, like Tulsidas, that you have this concept of Lakshman being Adisesha, Bharat being Panchajanya and Shatrughan being Sudarshan chakra.
But you are right that Vaikuntha is empty. Although in Krishna avatar, Rukmini did not precede Krishna or Balaram. After Krishna was killed by Jara, Arjun escorted all the civilians of Dwaraka to Mathura, and there, a number of Krishna's wives, including Rukmini, ended their lives, while some, like Satyabhama, took vanvas. (Also, the empty rule didn't follow during the first 6 avatars. In Matsya avatar, Vishnu didn't take Adisesha w/ him, using Vasuki instead to be a rope that Matsya used to pull the boat of the saptarshis. In Kurma avatar too, he didn't take Adisesha w/ him, and in Varaha, Narasimha, Vamana & Parashuram, he didn't take Lakshmi w/ him either. It's true that until Vamana, the avatars were short, but Parashuram was long lasting, but he remained a brahmachari)
I also doubt that either Brahma or Shiva summoned Krishna the way Brahma did Rama, since unlike Rama, Krishna knew that he was VIshnu, and knew that the curses of the rishis & Gandhari had taken effect. After he saw a snake leave Balaram's mouth, he went under a tree where he was shot by Jara.
I once posted this doubt in the Ramayan forum - if Vishnu & Lakshmi were still in Vaikuntha, why would the devas miss them, and why would Brahma send Kaal to Rama to tell him to return? The populace would have been happy to keep Rama, and the Devas would have happily had Vishnu w/ them.
Edited by _Vrish_ - 14 years ago