Warning: SPOILERS for Star Trek: Picard Season 1, Episode 5
Seven of Nine (Jeri Ryan) has ed Star Trek series so a team-up between Seven of Nine and Picard, who was once Locutus of Borg, is certainly a Star Trek fan's dream come true.
"Endgame", which was also the last time Seven of Nine was seen in Star Trek canon.
In Star Trek: Picard episode 4, "Absolute Candor", Seven staged a surprise rescue of Picard and beamed aboard his new ship, La Sirena, but fans didn't learn what she's been up to after Voyager ended until episode 5, "Stardust City Rag": In the years after the Romulan supernova, Seven of Nine left Earth to the Fenris Rangers, which is a vigilante group that patrols Romulan space helping people in need. Picard (and Starfleet) frowns on the Rangers for their "lawlessness" and for styling themselves as "judge, jury, and executioner", but as Seven explained her side of things, after Picard quit Starfleet and "gave up" when the Federation turned their backs on evacuating the Romulans, the Neutral Zone collapsed and the Beta Quadrant plunged into chaos. The Romulan Star Empire was no more and the Rangers, based from the planet Fenris, took it upon themselves to help keep the peace from the Romulan warlords who were springing up in the star system.
On one hand, it's noble that Seven of Nine became a galactic sheriff and action hero who helps the helpless, although it led to tragedy. In 2386, soon after becoming a Fenris Ranger under her human name, Annika was tricked by a crime lord named Bjayzl (Necar Zadegan), who wanted to harvest her Borg implants. Bjayzl kidnapped Icheb (Casey King), Seven's surrogate son who was also a reclaimed Borg introduced in Star Trek: Voyager, and violently stole his tech. Seven killed Icheb out of mercy and swore revenge on Bjayzl, which she finally exacted in "Stardust City Rag" by disintegrating the criminal with phaser rifles at point-blank range. However, it's disappointing that Seven of Nine's life was plunged into violence and pain in the decades after Voyager returned to Earth, to the point where she became a stone-cold killer.
Star Trek: Picard offered no hint of what became of Seven's relationship with Chakotay, besides the fact that it's obviously long over. It's also sad that Seven, who still struggles with affirming her lost humanity, didn't stay in artificial lifeforms were banned since much of her body still harbors Borg implants. So, Seven returned to space with the intention to help those in need after the Romulan supernova but she settled into the "hopeless, pointless, and exhausting" life of a vigilante, in Seven's own words. Trekkers had higher hopes for Seven of Nine so it's crushing to see the tragic turn her life has taken. However, Seven did offer Picard a way to her if he needs her help so, if and when Seven of Nine does return to Star Trek: Picard, hopefully, she'll spill some of the details about what became of Voyager's crew that fans are dying to know.
Star Trek: Picard streams Thursdays on CBS All-Access and Fridays internationally on Amazon Prime Video.