Evan was part of the Marauder-era gang of Slytherins that later became Death Eaters (Mulciber, Snape, Wilkes, and Bellatrix, among others). He was a participant in the First Wizarding War, and was tracked by a group of Aurors that included Alastor Moody and possibly Kingsley Shacklebolt. Evan, skilled at dueling since an early age, openly resisted capture along with his companion Wilkes, unlike most Death Eaters. He showed true bravery, as most Slytherins that dabbled in Dark Magic (such as Phineas Nigellus Black) called bravery fleeing to save your own skins. Evan was killed in a duel against Moody, but took a significant chunk out of his opponent's nose. He also was rumored to have been responsible for Alastor's glass eye, but this seems unlikely.  

Evan was probably the cousin of Bellatrix, Andromeda, and Narcissa, as their mother Druella would have been the correct age to be his aunt, and her maiden name was Rosier. Evan was also most likely descened from the original Rosier in Tom Riddle's gang.

Evan was named in Igor Karkaroff's bargain for freedom via Death Eater names, but was useless because, unknown to Karkaroff, he was already dead. Harry Potter viewed this in the Pensieve. 

Wilkes ultimately met the same fate, but less is known about him. He did not seem to be a very good duelist, as he could not deliver any injuries to Moody's posse of Aurors.