Jack is a former Faq unit. Jillian Zamussels refers to him as a master-class Foolamancer and genius at distractions. She also mentions that Jack may have had a crush on her. His Foolamancy skills were such that he was capable of veiling an entire settlement from observation. He was able to veil the cities of Faq one after another as determined by the Predictamancer of Faq and thus kept location of Faq hidden for a long time.Erf-b1-p107
His sanity was severely harmed either by being linked up with Misty and Maggie during Stanley the Tool's experiments into fusion magic or by Maggie severing the link and allowing the other two casters to take all the damageErf-b1-p084. He somewhat recovered after Parson and then Jillian addressed him by name.Erf-b1-p108Erf-b1-p113
Jack, like Wanda Firebaugh, seems to be extremely loyal to Lord Stanley.
Real World References
Jack Snipe's crush on Jillian is possibly related to "Jack and Jill."