Simple question duders, when will you meet Solaire the second time following his appearance just before the red dragon? I've been meaning to join the Warrior of Sunlight but he's not in his original position anymore.

Your second meeting with him is in Anor Londo by the third bonfire. You don't join the warrior of sunlight covenant through him though. You get to join that covenant by praying to an altar below the red drake you mentioned.

Oh I see, thanks!