On my first play through I recruited Erik The Slayer, Mjoll The Lioness and Annekke Crag-Jumper... the first two would just say something like they are there to serve me, very indifferent, but Annekke would always be saying "Wow, I'm a Blades now, I can't hardly believe it" like very excited about it... do you know any other character that reacts like that?
Went to the temple lots of time, did a couple of dragon hunts, never got a different line from them... once I saw that guy that Mjoll was living with visiting her, but never saw Annekke's husband too :P
The Dragonborn needs to speak to a follower and ask if they wish to become a Blade. Followers who can be asked to join the Blades are listed in the table below.
Once a follower becomes a Blade, they will move to Sky Haven Temple and are no longer found at their original location when dismissed. Once three followers become Blades, the "Dragon Hunting" quest becomes available which involves slaying a dragon at a random dragon lair with the new recruits. Should a recruit die, they cannot be replaced by inducting another follower.