i think unless my tired eyes deceive me they were both either in the same slytherin graduating class or close enough that they inevitably would've known each other during their school years!
as for the gremlin, in brief: life-long miscreant and ne'er-do-well, french expat, became an animagus in school exclusively to wriggle out of troublesome situations like choosing sides in wizarding wars, death hexes, being exploded and post-grad gainful employment. spent ?? years in a number of ultra wealthy witch/wizard/muggle households as a spoiled house cat that oft mysteriously disappeared around the same time as precious family valuables. a near-miss capture and threat of lengthy azkaban stay alarmed him enough to (try) to straighten out, with which he's doing his best. like, 10% of his best. unless it steps on any toes i'm hoping to sign him up as a very recent hogwarts hire as the new divination professor! his mum was a bohème seer and he's thrown enough runic dnd dice, consumed enough loose leaf tea and witnessed enough reading of animal entrails to fake having The Sight.
in briefer: ✅ pathological liar ✅ slytherin ✅ vermin