Star Trek: Everything We NOW Know About The Burn

For over a century, the Milky Way galaxy lived in fear of a second Burn. Though they were unaware of the cause, it turned out that they had every right to be frightened. Su'Kal, alone as he was on his world, was entertained by a complex holographic system created by his dying mother. It was the sight of her death that caused the first Burn. The possibility was ever-present for a second.

When Saru engaged with Su'Kal, the younger Kelpian (depending on how you look at it) offered Su'Kal his help. This was not just in rejoining the wider universe, but in facing the most devastating loss of his life. By accepting the death of his mother, Su'Kal was finally able to break his dependence on the holographic simulation. 

The process was risky. Su'Kal, connected still to the dilithium on the planet, could not be allowed to have another outburst that would send another shockwave through the galaxy. Had Saru been unable to calm him down, terminating him may have been the only option. Things got quite close to the wire as well, with Su'Kal struggling to accept reality and the need to face it.

Even after he was separated from the planet, Su'Kal needed care. This led to a leave of absence for Saru, which in turn led to Michael Burnham's promotion to captain of the USS Discovery. 

The Burn was a devastating event with over a century of fallout, but, in true Star Trek fashion, community and love helped to heal some of that pain.