I ended the game with 75% with Orion!
Day 2 saved Imperion’s daughter but let her go with her lover - ended with Orion at 60 or 65% iirc
Day 3 after getting caught by the cult, make sure you can escape from the cell by yourself (bring antivenom!) - I lost a lot of % with O when he saved me. then stick with him to defeat the cult and the Oxmother, and you get the 
romance:fire: scene with him.
He didn’t appear in Day 4 for me so everything I’ve listed should’ve had him at 75%.
Haven’t gone for Kyran yet though! Would love some tips!