I found Delenn very interesting in S1, then, as you implied, was disappointed by the direction they seemed to be going with her early in S2... until I realized once again that there was still a lot going on under the placid, loving, pious exterior. I love that she's really a profoundly ambiguous character under all of that holiness. Same is true of Sinclair and Sheridan, of course... I just don't like either of them all that much. I feel a resigned sort of fondness for Sheridan, but Sinclair is like nails on a blackboard for me a lot of the time. ;)

Maybe that's my favorite thing about Babylon 5 as a series - all the characters act under these fablous delusions and obsessions regarding themselves and the world around them. They're so wonderfully realistic, and yet completely over-the-top and legendary in both their flaws and their virtues.