Dressed as two eccentric professors, a Death Eater and Harry Potter himself, a family at the Fandemic convention was flagged every few seconds for photos.

The Ryall twins and their mother Carol David reveled in the attention during their second year at Fandemic, a comic pop culture convention this weekend at NRG Center.

The convention attempted its first stop in Huston in 2017, but was postponed by Hurricane Harvey until 2018. Around 4,000 fans are expected to attend this year to grab autographs and photos with their favorite celebrities from a variety of shows and movies, including This Is Us, Stranger Things and Hercules. The convention also features celebrity panels, artists and merchandise related to the characters fans love.

John Macaluso, Fandemic CEO, said he chose Houston for its large population and because he expected “great, nerdy, geeky, fantastic, wonderful fans.”

“Our staff is unique,” said Macaluso. “We bring in really fantastic celebrities, artists, vendors. I think we really care about the fans.”

Last year, the Harry Potter family costumes dressed up like 17th century superhero characters. They changed direction after finding out James and Oliver Phelps, the actors who play the Weasley twins in Harry Potter, would appear at the convention.

Elizabeth Ryall, 40, who was dressed as the stern and pink-loving Professor Dolores Umbridge, had every detail of her costume thought out down to the tea cups with kittens. Her sister, Rachel, 40, who played Bellatrix Lestrange, showed off her dark mark and called out to Lord Voldemort.

Meanwhile, their 68-year-old mother, David, who was dressed as Professor Trelawney, stroked her crystal ball. Rachel’s 5-year-old son, Aidan, wore a Harry Potter costume as he waved his wand and shouted spells.

Despite their nod to villains, the family said they were inspired by the good the saga evokes.

“I love that the good succeeds in the end,” said Elizabeth. “No matter how (much) evil comes against them they always win.”

Big name stars, like Milo Ventimiglia, were signing autographs for beaming fans. Ventimiglia, who is known for his role as the beloved father Jack on the hit television show “This is Us,” said he enjoys taking a break from set and truly interacting with the people who watch him.

“Sometimes what we do is a little one sided,” said Ventimiglia. “We’re on sets and we’re not actually getting a chance to talk to the people that are watching the things that were doing.”

Ventimiglia said his favorite part about playing Jack is that it inspires others to strive for their best.

“I like the fact that Jack is an obtainable superhero,” said Ventimiglia. “He’s someone that people can look up to. He’s realistic in terms of asking us to be better people. I think that’s a good thing, a thing we all kind of need right now.”

Kevin Sorbo, who played Hercules for the popular television series in the 1990s, was also signing autographs and posing for photos. He said even though his show ended years ago, people are still enthusiastic.

On Saturday, he said one emotional fan told him he watched the show with his mother who died five years ago.

“It’s all about giving back to the fans,” said Sorbo. “If you have no fans, you don’t have a career.”