Joani Jummp was introduced in the 1990s Jughead comic as a long-lost love of Jughead's from his childhood. Both had carried the torch for each other into their teenage years, leading to a happy reunion when Joani moved to Riverdale along with her stern, overbearing father and bullying older brother.
As Jughead was actively dating a girl named Debbie at the time, this created a new "Love Triangle", causing Jughead to be torn between two women. Joani's primary personality trait is a desperate, all-consuming love of Jughead, as she fawns over him and showers him with kisses. Unlike most girls in Riverdale, Joani has super-curly, semi-long hair, making her stand out in group shots.
We see a handful of Joani in the next couple years- usually one-offs as Jughead juggles two relationships. At one point, he tries to make money to date her, and ends up working for her father at the family restaurant. He doesn't approve of Jug, nor does "Junior", Joani's loutish brother, who has clearly given Jughead a black eye to show his disapproval. Joani's father is an abusive boss, constantly warning Jughead he's going to fire him if he keeps delaying, as he first makes time with Joani, then gets accosted by Ethel, and then Junior gets upset when Jughead "trifles with my sister's affections!" because he's seen talking to Betty and Veronica. In the final issue of the "Love Triangle" storyline, Jughead is dumped for good by Debbie, but when he figures he at least has one girl left ("The one I always wanted from the beginning!", he's given the horrible news- Joani's family is moving again, and to ALASKA this time.
Joani's father and brother shake hands, thinking "YES!" at the couple's sad moment, as they move to start a family restaurant chain in Alaska. Joani suggests "The only way I could stay here is if we GOT MARRIED!" and actually cuddles up to Jughead as she says it, which leaves Jughead flat on the ground in shock. She admits "but we're obviously not ready yet" to her stunned boyfriend. Joani thus leaves comics for good, never to return. Jughead proclaims that "I want to spend our last few minutes together just LOOKING at you...", and both are inconsolable as they part for good ("I love you, Jug! You're all I ever wanted!"). It's... a hell of a thing, really. The relationships themselves were handled clumsily (probably a victim of too many writers), but the break up was AMAZINGLY done and proof that Archie can handle some dramatic stuff.
Like Debbie, Joani appeared in Civil Chore in a single group-shot. She has far more covers than Debbie does, actually showing up on the very first Jughead Double Digest and a handful of Archie's Pal Jughead comics.