Pretty Little Liars: Original Sin season 2 is officially set to bring back a character from the original series. Pretty Little Liars, which follows a group of teenagers who are being tormented by a killer known only as A, originally ran for seven seasons between 2010 and 2017. Although there have been several spinoffs and reboots of the show in the meantime, the series was most recently rebooted last year for HBO Max as Pretty Little Liars: Original Sin, taking on an even more slasher-style genre angle.

https://screenrant.com/pretty-little-liars-summer-school-dr-sullivan-returning/