Severitus

Severitus is the familyship between Harry Potter and Severus Snape from the Harry Potter fandom.

Fanon
This ship is when a fanfiction describes a situation in which Snape becomes a father-figure to Harry in some way; this often involves Snape being obliged to adopt Harry after his parents' deaths or similar.

Fandom
AO3

Variations

 * Snarry – the slash pairing between Harry and Snape