It is implied in a flashback that one of the major characters attempted suicide through an abnormality "Bottle of Tears" by purposefully triggering it's ability + minor/background characters.
Certain characters are shown to get violent due to "mental corruption", but mental illnesses are not directly mentioned or implied and this is rather a cause of the corporations conditions.
The entire cast of the comic are canonically nonbinary, and many characters are killed. The fact that they are LGBT is not at all relevant to any of them.
Nobody drowns on-page, but there is an abnormality known as the Drowned Sisters which implies such. Underwater imagery is also used occasionally, but not drowning.
See "does the dog die".
However, suppressed animal-like abnormalities simply return to a previous, more docile form, and do not appear as if they have been killed
The first corpse shown is of someone with dark skin, however, multiple characters die and their race is completely unrelevant to their development and cause of death.