Vladco Heiress au is constantly on loop in my head so here my ideas for the other DP characters:
Jazz - researcher psychologist with a focus on socio-cultural psychology. After Danny manages to come to a compromise with his rouges, creating a long-term truce, she becomes interested in cultural differences between Realm beings and Amity Parkers & later on how the two cultures started to blend and form unique social norms.
Tucker - didn’t go to college and just started immediately working at Vladco as Danny's assistant/advisor to help him out while he figured out how to run the company. Once Danny started getting things under control Tucker became an engineer (still at Vladco) to focus on his inventions.
Sam - she properly sat down with her parents and talked to them leading to them realizing they have been acting unreasonably and compromising. Her dad offers to teach her and Danny both business and how to lead a company as an olive branch. I imagine her family has a successful telecommunication company but for now her dad is running the company so Sam can start her own company which creates and researches eco-friendly solutions (e.g biodegradable plastics) while working with a bunch of eco charities.
Valerie - in my au she joins the Phantom team during 50 Shades Of Valerie Grey. The team has trouble trusting her at first but eventually they become close friends. I imagine that she took some odd jobs after high school trying to support her dad and then ended up with a security job she enjoyed. Once Ellie started traveling Danny hired her to act as Ellie's bodyguard because she's the only person he could trust keep Ellie safe. Whenever she's back in Amity she meets up with Danny and Tucker to have geek out sessions where they create ridiculous technology while not sleeping for 3 days.
Wes - became part of Team Phantom after Val but before the release of Pariah Dark. Became an investigative journalist so he travels a lot - this and his tendency to hyper fixate on his articles means that he's horrible at keeping in touch with people. He's closest with Valerie (she was the first one to properly accept him onto the team) and Ellie (they meet up whenever they are in same city and compare notes about rich people - Wes tells her which CEO's he thinks are doing shady shit and she tells him which rich people gave her bad vibes or are assholes).
dpxdc au with Serious Chaos, background Danny/Sam
Vlad gets an officially trial because of a domino effect caused by him releasing Pariah Dark. The release of the old king was such a scare to the Realms population, with him being extremely powerful and having committed grave atrocities towards the end of his reign, it led to the ancients, observant and the majority of the inhabitants of the Realms deciding that they need to create a functional government to prevent something like this happening again and to keep the Realms safe. However, forming a working government and catching Vlad to get him trialed takes time so Kindered Spirits still happens. Vlad's trial has thousands of angry ghosts watching from the sidelines while the judge announces a long of crimes the council of Ancients found him guilty of and then presents the supporting rock hard evidence. His sentence is being souped for the next 600 years - which a lot of ghosts still think too lenient.
When Danny defeated Pariah Dark he became the rightful ghost king but Clockwork told him that the council of ancients can act as the main governing body in the IR for now and suggested that Danny could take over Vladco (Vlad left to Danny in him will) to gain experience for when he becomes king.
After a few years, Elysium "Ellie" Phantom decides to return to Amity, partially because she already traveled the entire globe and partially because she feels safe being in Amity now that Vlad is gone and she's had time to work through her trauma. Her travels have made her a great negotiator so Danny decides to name her heiress. Officially Danny is CEO but Ellie handles most of the CEO's responsibilities (being the face of the company, has meeting with shareholders, discuss projects with other CEOs/representative of other companies) while Danny acts more like a COO (oversees different operations, facilitates communication between departments, coordinates product manufacturing and quality control).
Damian starts investigating Dalvco and Ellie specifically after she approaches him at a gala hosted by the Wayne family in Gotham. Dalvoco was probably on the bats radar as a sketchy company and they suspected something shady was going on - either because of Vlad's business strategy in general or due to ties to Lex Luthor - but other things kept taking priority considering the craziness of ghotam, how often villains try to destroy/take over the world and the lack of hard evidence of Vlad's wrong doing - they just felt something was off. Plus, Danny is a recluse, staying in Amity and avoiding the media, so when they saw Ellie the batfam is kinda hit in the face that yeah this company does still exist and hey look it looks even more shady now (Vlad just disappeared out of nowhere and a kid who he allegedly had an VERY antagonistic relationship with inherited his company).