Manbearcat
Legend
Break and Suffer are qualitative. Neither are likely but both are possible regardless of who controls the patron.
If you have a player that controls the patron and doesn't build in suitable restrictions or consequences - then you're playing a mage with a supernatural friend that can be expected to have resources that the player will try to take advantage of - because they already did not build in suitable restrictions or consequences.
If you have a DM that controls the patron and doesn't give the player a clear set of rules to avoid consequences - then you've got a DM who is setting the player up to fail - because he or she has already shown that they're not going to do the work to ensure the character is viable.
Most relationships will end up in between these two extremes but it's always a good idea to separate the duties of player and DM along the expected lines and find the comfortable spot that works for both the DM and the player and not start with player enablement until the two of them feel each other out.
Here is a different kind of a patron (than an otherworldly, divine benefactor) from the Dashing Hero (Errol Flynn/The Princess Bride genre tropes) Dungeon World playbook:
A Lover In Every Port (CHA)
When you enter a town that you’ve been to before (your call), roll +CHA. On a 10+, there’s an old flame of yours who is willing to assist you somehow. On a 7-9, they’re willing to help you, for a price. On a miss, your romantic misadventures make life more complicated for the party.
This move involves the following dynamics:
1) The player choose whether a patron (an old flame) is introduced into the gamestate.
2) The resolution mechanics determines the implications of (1) on the gamestate.
3) The GM engineers the backstory in accordance with (2) (constrained by the GM's agenda/principles and the rest of the fiction).
Let us say the Swashbuckler had some sort of 5e analog to this. Or let us say the Samurai had something like this (but sub ex-lover for ex-nemesis that you spared in a duel). Why would a particular 5e game suffer for its use (if you feel it would) while Dungeon World games are enriched by it?