Or at the very least, related to the Tales of Zestiria the X anime.
This rumor, though not that widespread, has been floating around ever since Tales of Berseria and the Tales of Zestiria the X anime (formerly named Tales of 20th Anniversary Animation) was first announced. Specifically, a particular symbol on the back of that new character shown in the original Tales of Zestiria the X trailer was also seen on a town banner in some screenshots or scans of Tales of Berseria:
Granted, the design is not 100% identical, but the pattern itself is highly similar.
Back then, it wasn't concrete yet if there was a connection between the two, as some defended that the "Tales of 20th Anniversary Animation" might not only be about Zestiria, given its name. Now that it's been now renamed as Tales of Zestiria the X, it seems to be leaning more toward some sort of connection between the two games.
Cue in the new Tales of Berseria trailer. Some things in the trailer have caught fans' eyes. Specifically, the following:
^Going back to that symbol seen in the Berseria screens and the Zestiria X trailer, it appears once again on the cape of the knight that was fighting Velvet.
Speaking of the said knight, some find the two men accompanying him to be similar in design to what we know was some of the Seraphim in Tales of Zestiria, specifically the ones that are in the trials. Actually related? Or just some sort of model recycling?
^Is this someone turning into a hellion?
^Or is this a hellion?
The following assumptions made by fans may seem far fetched to some, but they've been raised multiple times so I thought I'd add them in:
^Some are saying Velvet's transforming arm thing may possibly because she's part hellion or has been corrupted by one?
^Or that Lifiset is a seraphim mainly because he seems to wield seraphic artes and that the ends/tips of his hair is a different color (though I think this is better confirmed with art from ufotable). The latest news from Shonen Jump states Lifiset as a "spirit" though. In Berseria's world, spirits are apparently used as slaves. With that said, they're probably entities people can see, so that sort of crosses this out by a tiny bit.
Note that all the points we raised above are just mere rumors for now and is not official news. Is it true? Only time will tell. For now, let's have fun with the speculation embargo.
Tales of Berseria is the latest mothership title of the Tales of Series which was first announced during Tales of Festival 2015. The game was released for both the PS3 and PS4 on August 18, 2016 in Japan, January 24, 2017 in North America and January 27, 2017 in Europe for the PS4 and PC. The game features a female protagonist named Velvet and a theme of pirates and ships. It’s also confirmed as a distant prequel to Tales of Zestiria.
Tales of Zestiria is the Tales of 20th anniversary title and was released in Japan for the PS3 on January 22, 2015 and for the PS4 on July 7, 2016. It was also released in North America and Europe for the PS3, PS4 and PC Digital on October 16 and 20, 2015. The game features Sorey, a young man set out to be the Shepherd. The game is a distant sequel to Tales of Berseria. An anime series by ufotable, called Tales of Zestiria the X is currently airing worldwide.
The Tales of Zestiria the X anime (read as “the Cross”) is a TV series adaptation of Tales of Zestiria that was first announced during Tales of Festival 2015 as the “Tales of 20th Anniversary Animation”. The animation is done by ufotable. The first season aired during Summer 2016, with a second season confirmed for 2017. Its tagline is “The Journeys of the Shepherd go beyond Zestiria,” and shows hints of connections with Tales of Berseria. 
