I would most likely think it is a snake when he was in Hogwarts

@icecreamdif plural is Patroni by the way. Same like Animagi 😉 but I totally agree with what you said of course. Good point!

Thanks

He didn't have one. To produce one, you have to have a happy memory in mind. I don't think he had many happy memory's.

LeaLupin-Here's an excerpt from Deathly Hallows. "When the patronuses glided out of the dungeon there were cries of shock from the people waiting outside."

And, here's one from Order of the Phoenix "The few patronuses people had managed to conjure faded away into silver mist..."

The books always use "patronuses" as the plural.

He won't have one because he doesn't have any happy memories

I think it was a snake for the main reason his most prized possession was nagini and modeled his image after a snake

although he doesnt have one, nagini or a basilisk

Even though he doesn't have one because he doesn't have happy memories of he did it would be a snake

I looked it up and jkr said that he didn't have one bc he doesn't have any happy memories but if did have one it would be a snake