As Inferno begins to engulf Krakoa, it's notable that some teasers for the event hinted at traitors moving behind the scenes on the mutant nation. Colossus has already been revealed to be one such figure, but another suspect actually has a history of betraying the X-Men.
Bishop's original betrayal of the X-Men during Messiah Complex revealed how far the time-displaced mutant is willing to go to change the future for the better -- no matter the bloody cost it may entail.
Hailing from a dark future where mutants and humanity had eventually gone to war, Bishop eventually ended up trapped in the present. He became an X-Man, and served honorably with the team for years. Although he initially tried to alter some elements of the past (like discovering the identity of a traitor to the X-Men), he never tried to make massive changes to the timeline until the events of the Messiah Complex crossover. In the aftermath of Decimation depowering almost all mutants on Earth, the X-Men regrouped and did their best to protect their remaining students and allies. The birth of who would grow up to become Hope Summers changed everything -- making her the first mutant born since the Decimation began and setting up the return of more mutants (and the potential for a mutant/human war).
Cable moved to protect her, while Bishop made a dark decision: deciding that he didn't want to risk Earth-616 becoming the kind of timeline he'd grown up within, he betrayed the X-Men and planned to kill Hope before she could grow up and change the world forever. He set off Nano-Sentinels within the O.N.E. Sentinel Squad, killing the human pilots and pitting the Sentinels against the X-Men. He then ambushed Forge in the chaos, laying a trap to capture Cable and kill Hope. By the end of the event, his crimes had been exposed -- with Bishop escaping their custody even after firing on Hope and instead striking (and nearly killing) Charles Xavier. After replacing his torn-off arm with a stolen mechanical one from Forge, Bishop chased after his fellow time traveler.
Bishop became the overarching villain for the following volume of Cable, which focused largely on the titular time-traveling mutant making his way across the time-stream while trying to protect his adopted daughter before her eventual role in deciding the fate of the mutant race. His actions -- including laying traps across the course of time and eventually even working with the villainous Stryfe out of a newfound obsession with killing Hope. Eventually, Cable was able to defeat him and strand Bishop in a distant dark potential future. Eventual encounters with the Demon Bear of that period resulted in Bishop being sent back to the present day -- and gave Storm and Psylocke the chance to remove this obsession with killing Hope from his mind, helping restore him to a more heroic form.
Since then, Bishop has made peace with Hope, who showed restraint and refused to kill a wounded and defeated Bishop when she had the chance. The time-displaced X-Man rejoined the X-Men and resumed his heroic duties -- eventually even becoming a War Captain of the Krakoa era. He was even recently promoted to the rank of Captain Commander, making him more or less the leader of Krakoa's emergency military. But none of that erases the fact that across his hunt for Cable and Hope, Bishop technically killed countless civilians throughout the time-stream. Bishop's betrayal of the X-Men in Messiah Complex was a major deviation for the character but proves that he will sometimes choose to follow his own personal mission rather than work within the goals and dreams of his fellow mutant heroes.
If Bishop was willing to betray the X-Men once in a bid to change the timeline, what could happen if he learns about the dark potential fates witnessed by Moira MacTaggert? From his current position, Bishop could lead Krakoa into ruin if he believed it would be for the best -- and given his past choices, it's not out of the realm of possibility that he would do so.