Tsin and Rosh, be aware and keep watch: A longtime "friend" of your major rivals who suddenly appears as though he is aggressively trying to befriend you may not really be seeking for genuine friendship. As you may have noticed, a lot of motives are involved here, some are obvious, while others are not so obvious.
He is your rivals' "friend" who is harboring hatred against his longtime "friends" because his ego cannot handle constructive criticism from them. He wrongly thinks they ganged up on criticizing him so he retaliates by hurling fierce insults and curses against them and he is trying to cut relations with them. Now he is trying to play his favorite dangerous and trickery-laden "Pildi-Gana" game by trying to befriend both of you so as to separate himself from them and to seemingly annoy them and to attempt hurting their international credibility. Potentially he could become a good friend to you or he could also turn out to be not a truly good friend in the long run. Understand all of his ways and maneuverings thoroughly.
Be careful how you treat him. While blessings may be upon those who understand his misery, curses shall come upon those who take advantage of him and his situation. You can show him though some degree of magnanimity to show and give him a taste of your respect. But withhold showing eagerness to accept all of his proposals and be careful not to rush taking every word he says simplistically at face value. He is a hurting soul and he is harboring a wounded ego and he could just be seeking for some company because of his self-inflicted misery.
Tsin and Rosh, exercise wisdom. He could be as if a tempting coy smile to you, but he could also turn out to be a self-manipulated ego-wounded seeker of alliance (for reasons of expediency) that your rivals could find ways to take advantage of and use as some kind of an unwitting decoy to your disadvantage.
Keep a keen watch on everything that is going on. Never forget that the name of the game is "Pildi-Gana": Winner loses; loser wins. Thus be as well very prudent and discerning with every move you may decide to make. After all, both of you have long been major players in this nasty old game anyway.