His fight with Syria ended with Syrian withdrawal. Yes, it ended because Aoun could not wage an international war against a neighboring country. First, he is not at the head of the Lebanese state. Second, it is against international law.
As of joining ranks with whoever, Aoun has formulated his own political program covering fighting corruption. Whoever joins rank with him, agrees for that whole program. Corruption goes back to the Hariri 12-year PM era, having resulted in a $44 Billion debt. Aoun is asking for an independent, if possible international audit into the lebanese government finances for that period. The "opposition" has formed a coalition from an all former pro-Syrian politicians to counter this audit. This audit would have a crystal clear result, that of unmasking to whose pockets went those $44 BN. Everybody in Lebanon would tell you that they went both to the pockets of the Syrian Nomenklatura, the Syrian intelligence apparatus posted in Lebabon, and those same people who claim now they are anti-Syrian.
Thank you for the thorough explanation.