I see your “keith is the only one affected by lance’s pickup lines” and I raise you “Keith wildly misinterprets all of lance’s pickup lines”.
The lines for those that don’t know them:
I’m homesick for earth, but I’m lovesick for you.
I think you’re purr-fect.
You’re outta this world, and I would know!
I better use ice blast… because my heart’s on fire.
The one that does work of course is the first pickup line on the official list. Maybe one day I’ll draw Keith’s reaction to that one!