The word "random" is ill chosen. I mean it to include any and all sorcery that does not fall into the three other culture blocs. So, if you don't like any of the other ideas you still have some options, though you're likely to be considered unusual and strange in this campaign--even more so than a normal sorcerer.

This is a good choice for characters with the Lore descriptions Naive or Adept--generally, you either have no clue what you're doing, or have gained great understanding despite a steep learning curve.

Random Demon Ideas

As a general rule, these demons don't play nice. They're tricky, hostile, or otherwise difficult to control, which is why they don't show up among the more sensible traditions.

Astral Worm-Spore

This is a Parasite demon--a sentient disease colony that infests your body and confers strange abilities. Perhaps you were infected during a foolhardy trip to the Astral Plane? Powers include Link, Perception (Astral Plane), Spawn, and Special Non-Lethal Damage.

First Age Artifact

An Object demon that somehow survived the destruction of the First Age; these are powerful and absurdly rare. Powers may vary.

Rogue Djinn

The djinni are described on the Hermetic Sorcery page. They live in the City of Brass and have their own government, but this one might be a criminal, outcast, or malcontent. It probably hopes to exploit you somehow. It is an Inconspicuous demon.

Sartarim

The sartarim are qlippothic cockroaches who infest the dark places of the earth. They're about two feet tall, but have the strength of a grown man; they'd be dangerous if they weren't so stupid. These Passer demons may Pact but cannot Bind; you Contact them by sharing a stew of your own piss, shit, and puke. Powers: Armor, Fast, and (for the larger queens with higher Stamina) Spawn. Their Desire is always Ruin, and they Need to eat filth.

Random Drugs

Sorcerers in this tradition probably use hallucinogens and other crazy substances to perform Contact rituals, since they don't know the standard lore. Some of these substances can help you perceive or travel to the Astral Plane.