A one from day one
The person who never left your side, even when you were a complete mess and probably smelled like a garbage can.
My one from day one never left me, even when I cried in public over a failed video game.
Since the first day of college, my one from day one was there, even when I slept through every class.
He’s been with me since day one, even when I took his phone and played TikTok for six hours straight.