While Sully's return to "Bones" Season 12 has been long revealed, latest spoilers suggest that his comeback may have caused Brennan & Booth's marriage at stake. It is also speculated that two characters will not make it in the last episode of the last season.

Right after Season 11 ended, reports have already surfaced that "Bones" will have another season that serves as its final installment. Previous spoilers hinted that Season 12 will enlist the presence of the fan favorite characters including Stephen Fry, Betty White among others.

Furthermore, it has also reported that Eddie McClintock is returning to reprise his role as Tim "Sully" Sullivan, Dr. Brennan's love interest in Season 2. Since this is final season, it is expected that his character will be messing up with Booth and Brennan's marriage. As per Deadline, "old flames" will surface and put a strain on somebody's marriage.

Apart from the "old flames," unfinish business will also be put to an end in "Bones" Season 12. The elusive Puppeteer will still be playing a big role in the final season. Reports also say that he will kill two characters during this season, and one might be a main character.  But co-showrunner revealed during San Diego Comic-Con that the persons to be killed off are not any of the series regular.

Emily Deschanel also reveals to TVLine that in Season 12, "there's going to be some sadness in the [next] season." The actress is probably pointing out the strain on her character's relationship with Booth, if not about the death of two characters.

Meanwhile, the 94-year-old actress Betty White is also bound to reprise her role as Dr. Beth Mayer in "Bones" Season 12. Mayer is the world's most experienced forensic anthropologist appeared last season. Mstars News recently reports that she will be seen until the very end of the series.

"Bones" Season 12 Episode 1 airs on January 3, 2017, Tuesday on FOX.