After all, Oliver needs his family by his side now more than ever.
Of course, she ended up being the leader for the Ninth Circle and, suffice it to say, her relationship with Oliver never really recovered after that.
After she left, Arrow attempted to fill the void of Oliver’s disappearing family members by bringing in Emiko, his half-sister and Robert Queen’s secret daughter, in Season 7.
Thea’s return is highly anticipated and much needed, especially now that Oliver will be facing death and a new mission for The Monitor ahead of the Arrow-verse crossover, “Crisis on Infinite Earths”.