Manuel is, typically, not one to brew his own coffee. When you have money and power, it's simple to have someone weaker do it for you- whether via paying them, or by giving them the right motivation to cozy up to your good side.
Magneto isn't paying Manuel (thankfully, as a refund would be in order.) He didn't ask for the coffee at all, to be fair. But, Manuel presents it as an act of submission, all the same.
No one here seems to respect him on the virtue of being Emma Frost's favorite alone. But, if he can play his cards right… maybe being the favorite of multiple authority figures could win him some favor.
Unfortunately, Magneto doesn't seem on board with his plan. Ugh. Maybe he should've had someone else make the coffee and just stolen the credit for it.
Reflex is to sneak into Magneto's mind, to flood him with affection and gratitude since he clearly doesn't understand how this is supposed to go.
He holds back. Magneto knows him too well to not notice. He's only going to be able to use his powers on Magneto once, maybe twice, without repercussions. This isn't the hill he wants to die on.
“If I were holding a grudge…” He flashes what is presumably supposed to be a charming smile, but there's irritation in his eyes, “I wouldn't have made you coffee to begin with.”