It's quite obvious to me what Kira saw in him: someone she could come to rest with, feel safe with. She's been through so much, she's that fucked-up by her experiences, someone a lot more stable than herself would appeal. And the last kind of person she would ever get on with is someone with the same fiery temper - they'd just be throwing things at one another the whole time.
O.k. so he wasn't the most exciting character, I agree, but I don't understand all the bashing he gets (I've said that before). I've always liked him. He seems a very caring and gentle sort, and he does have a little streak of irreverence for the prevailing religious dogma that I for one thought made him exactly suited to his station in life. Religious ideas wouldn't be misused for the persecution of others half so much if more sefl-professed believers had such a relaxed mindset.