I meant more as an assessment of their relationship as a whole, not individual incidents.

Yes, he did change and once it's settles down from about episode 5, their dynamic shifts subtly again. The question of leadership is an interesting one - I've never felt, personally, that it's a question of 'Now one leads, now the other' - it seems much more fluid to me.
Yes, Delenn has more knowledge of what's going on, but Sheridan does make a lot of choices on his own.