|“||Aldous is two thousand years old. He's capable of anything.||”|
–Magnus about Aldous, The Rise of the Hotel Dumort
Supposedly born into the world early, Aldous apparently lived for almost two thousand years. By 1929, he had already become the High Warlock of Manhattan. With the passage of time, however, Aldous had become very powerful but also eccentric, losing bits of his sanity the longer he lived in isolation.
Although he had grown sick of mundane ways and the world they lived in, he allowed himself to be hired by mundanes so he could live at the Hotel Dumont. During this period, he studied a way to open a Portal to Pandemonium in the Void, otherwise known as Hell, where his parentage resided. Aldous had also correctly predicted the crash of the stock market.
The day the stock market crashed, Aldous completed the final part of his Portal. He offered Magnus the chance to join him in what he considered to be their true home. Magnus refused but didn't stop Aldous from trying to complete the final piece: sacrificing warlock blood. Before he could do so, however, a Shadowhunter shot him with an arrow. Regardless, his blood dripped into the spell and activated the channel. His body was ultimately consumed by the Portal and, according to Magnus's mysterious father, has joined his brethren, in a way allowing him to fulfill his goal of living in the Void.
Aldous was literally an old warlock, not only old in years but also in appearance, looking like an old man in his late fifties, with a white beard and white hair and had to use a black cane to help him walk; whether he stopped aging late or his appearance progressed over the centuries is unknown. His warlock's mark was clawed hands and feet.