Connor - he promised you he'd always stand by your side no matter what the circumstances were, even in life or death. You knew Connor wouldn't go back on his word and he'd proved it a few times as well.
Markus - he promised that he would always protect you from anything as your life was singlehandedly the most important thing to him.
Kara - she promised to always make you laugh because when you were happy, so was she.
Gavin - he promised to never leave you and he also said that if anyone were to ever get hurt in your relationship, it would be him because he didn't want to ever see you get hurt.
North - she promised to take care of you whenever you were ill or sad or even happy because you meant everything to her.
Luther - he promised to always make you smile at least once or twice every day because your smile brightened up his world.
RK900 - he promised to always love you - he knew he didn't need to promise because he knew he wouldn't stop loving you but it was more to ease your mind - and he would love you more than anything that could ever exist in this universe.
Ralph - he promised to always make you happy through whatever means possible.
Kamski - his promise was to never let you down because when you were unhappy it made him unhappy.
Simon - he promised to always listen to you.
Josh - he promised to always make you feel loved whenever you were around him.