cut our teeth and make our bones right here

Remi

Welcome to the wild, no heroes and villains
Welcome to the war, we've only begun

Given that the wendigo's system has seemingly shut down while it attempts to burn away the remaining serum within it, the addition of adrenaline in trying to counteract this produces a very interesting if not predictable result: seizures.

Remi's muscles tense and then spasm as the adrenaline is fought off by the wendigo's metabolism, leaving Remi looking like a man constantly being shocked by a defibrillator. It's a mercy that his pain receptors are quite dull, because had he been human for this, the pain might have knocked him unconscious. If anything that might have been a blessing given the shock and stress his system was currently under.

Every time the adrenaline succeeded in finding purchase, the wendigo's skin would seemingly melt away leaving only bone and ugly muscle. The skin of his face would peel back revealing only a skull and glaring golden eyes, before his metabolism was able to fight back, reasserting control and covering Remi's body with appropriately placed muscle, bone, and skin. Not unlike a cartoon of someone being electrocuted where they go from skeleton to human and back again with each flash, so too did the wendigo flit between bodies.

Higher and higher you chase it
It's deep in your blood, go and take it

Code blatently stolen from queen of codes, Sky!