Citan, also known as Doc in the beginning, is the somewhat eccentric doctor that lives in the mountains near Lahan with his wife, Yui, and his quiet daughter, Midori. He likes to build weird things (like the spider-copter) and collect ancient objects. He is the one who warns Fei not to fight in the village with the Gear when they other Gears begin fighting. He also is the one who later on constantly tries to get Fei into Weltall. Not much is known about his past and how he knows so much about Solaris until later on when he meets Sigurd again.
[Personality]
Citan...well, he talks a lot. He probably talks more than everyone in the game combined. He's also "the brains" of the group. He is the one who knows practically everything that's going to happen, but usually doesn't have a plan. It's comical to hear him explain serious and confusing things, only to then hear him say he has no idea what they should do. Sometimes he pretends he knows what he's doing, like when Fei gets an exploding collar on his neck in Norturne, Citan makes it worse by accidently taking the safety part off. Later on in the game he switches from using his fists like Fei, to using a sword, as does his Omnigear, Fenrir, does.
[The Truth]
Warning! This section explains nearly everything about Citan. If you don't want to know, then don't read!
Not all that much about Citan as there is Elly and Fei. Citan was actually from Solaris. There, his name was Hyuga. He and Sigurd eventually were able to escape when they were sick of what Solaris was doing...or so they say. Citan was supposed to watch the -Contact- for the Emperor (the so-called leader of Solaris) and destroy him if he were a danger. You learn this later on in the game when Fei and the others are caught. This part got me pretty pissed off at Citan, until he explained the rest and we were sure he was on our side still.