An SIFic is a self-insert fanfic, sometimes referred to as a portal fantasy in some circles. As any other genre of fanfic, it may be good, bad, and anywhere in between. However, SIFics in particular tend to be done with only a limited amount of success, since self-inserts commonly tread an even finer line with Mary Sues than original characters do. The particular danger: the temptation to live out a pure fantasy often takes precedence over respect for canon. This typically results in the SI doing things they shouldn't be able to, such as communicating with canon characters who speak a different language, displaying skills they could not reasonably acquire, and causing canon characters to fawn over them for no good reason.