1) Read the wookieepedia entries on him and the Dark Times. Look for Jedi during the Dark Times and even a bit of The Rise of Empire comic. Some Jedi went to get revenge on Vader and some realized that would be foolish.
2) Look at where he is and think about how he got there:
-He was one of the few Jedi that didn't trust the gift of the Clones. This meant that either his upbringing or master taught him to look past the benefits or be at least somewhat skeptical of things that appear to be gifts
-He also was a leader during the Clone Wars and had to have independent units trust him but this also meant he had to have allied Jedi either not believe in his ideas or they reluctantly went with the Council instead of his insistence. This would lead to some serious survivor's remorse. Imagine having all of your friends die because of something you suspected. This would probably want him to do more next time to stop it.
-he was a leader with independent units, which I mentioned, this would lead to the conclusion that he was able to relate to his men and their problems.. You don't get independent units to function as an army without communicating and a bit of empathy to the cause. In other words, despite his suspicion, he realized that individuality was probably more necessary than unflinching devotion of the clones.
-He was apparently very likable outside of the battles but switched to serious "game face" during the battle. However, after seeing the results of the clone wars, he, at this time in 2 years, probably is still battling some melancholy and not the same likeable man. He would definitely be focusing on trying to find ways to be a thorn in the side of the growing Empire and this may have put him a bit more in the cold, detached frame of mind that would pass before the events of TFU.
-Living off the grid would probably also make sure he moved around alot and purchases simple. He had to be using aliases until he felt he had a suitable militia. If you were a general for the Republic and then the genocide of Jedi took place, you know the name "Rohm Kota" would probably red flag you. Two years after the fact, he would be keeping a low profile while still communicating with some of his more trusted contacts. That being said, he would be even more focused on how much trust he put in those contacts.
-Trust in the force. The man, in the games, showed that he looked to the force for guidance and brief glimpses of the future. I am sure that he probably waned from the force for a while as it did jack for his brethren (one can debate how much the force helped and hurt in other discussions). This would probably even shake the staunchest Force trusters.

I am certain I probably contradicted myself here and there but this guy probably stayed low and out of sight for a while and that would probably mean a bit of personality changes along the way: Hide but scheme. Don't be vengeful (Dark Side focus) but definitely be ever vigilant. Be pragmatic but suspicious. Slowly regain confidence in the force but know that it is limited in a way.