Parabatai pairings are rare in the Shadowhunting world, but if you're trying to train alone in the mundane world, I'm afraid your chances of failing are terribly high.
Possible parabatai's must be a fellow mundane who wishes to Ascend to become a Shadowhunter. They may have also read the scribe Cassandra's books of records, the Dark Artifices, the Mortal Instruments and the Infernal Devices.