Tyrell

Tyrell (Terrell in the Japanese version) is a playable character in Golden Sun: Dark Dawn. He is believed by many fans to be the son of Garet, and is likely a Mars Adept himself. He was first revealed for the game alongside his fellow party members Karis and Matthew.

As a playable character
It is evident from trailers that he is one of the main party members that appears in battles in Dark Dawn, and he uses a similar collection of Psynergy as Garet did in Golden Sun, indicating his element as a Mars Adept. The E3 2010 floor demo footage showing him in battle shows him launching a fiery Psynergy in battle that looks like a 3D rendition of the Fire Psynergy series. In the floor demo's Battle Mode, Tyrell has the Mars Djinn Fever and Torch Set onto him, and his Psynergy consists of Heat Wave, Flare and Flare Wall, "Starburst" (formerly Blast) and Nova, Volcano, and Fireball. Whether he also has the Move Psynergy like his father did, in a similar case to Matthew and Isaac, remains to be seen.

Biography
Tyrell is considered the son of the previous games' Garet on the basis of very similar appearance and what is confirmed from press releases that 30 years had passed in between Golden Sun: The Lost Age and Golden Sun: Dark Dawn and that the main characters of the game are the children of the main characters from the previous games. What is interesting to note, though, is that while he has a similar build, hair style, and hair color to Garet, his light blue eye color is much different from Garet's auburn eye color. For whatever reason, Tyrell isn't present on screen along with Matthew and Karis in the scene E3 2010 trailer when a Psynergy Vortex appears near the town they are at, and he is not present in battles when Matthew and Karis are accompanied by two other adult characters.

Art and screenshot confusion
A point of contention among the fanbase that surfaced shortly after the posting of Tyrell's official artwork pictured at the top is what appeared to some eyes as dissimilarities between the design of Tyrell's portrait and the profile in the image to the left, which came from the E3 2009 promotional poster. Some perceive differences in hair color and/or wardrobe - which would be strange if that were the case, since Matthew and Karis are consistent in all aspects of their design between their appearances in the 2009 poster and their 2010 artworks - which leads some to assert that these are separate characters. Others may assert that this is simply a redesign of Tyrell that transpired in between his appearance in the 2009 poster and the 2010 footage.

Evidence exists to suggest that both of these assertions are unlikely. Battle screenshots like clearly show and name Tyrell as accompanying Matthew and Karis, where the noticeably bright red color of his hair and the bold yellow color on parts of his shirt matches the top portrait exactly. In point of fact, it matches the left profile as well, but this is only apparent through a thorough study of both images; in the profile to the left, white stripes on the upper parts of the sleeves can still be made out, and so can what appears to be a green metallic portion just underneath the upper part of the back area, which would wrap around the torso. Both of these elements are consistent with the design of the Tyrell portrait shown up on top, and this seems to show that the culprit behind the apparently darker hair color and different clothing color on Tyrell in the 2009 poster is the coloring and lighting in the scene. That there is no character or design difference between the two images is further strengthened by the limited battle footage shown at the floor demo from E3 2009, which shows that the Adept battling alongside Matthew and Karis is clearly the same design as Tyrell's portrait above, having the same noticeably-bright-red hair style and set of clothes. This proves that Tyrell was already designed as he appears today by the time of his first appearance in E3 2009.

Something else which added more Tyrell-related confusion was released at the same time as the official Tyrell portrait at the top: The pictured battle screenshot to the right depicts a battle scene where Matthew and Karis are accompanied by two other party members whose identities are currently unknown, the leftmost of which is a character with spiky brown hair resembling Tyrell somewhat, but with noticeably darker, outright brownish hair, and a brown leather jacket. Some thought that this is Tyrell too, but it's specifically because of this character's darker hair and brown jacket that this is highly unlikely, despite similarities in other areas. Other differences include eyes that show no trace of light blue, and he also seems taller than Matthew even if it is considered how much larger he would artificially appear by virtue of being closer to the camera in the screen. Other screens that depict the real Tyrell seem to depict him as no more than one or two inches taller than the other Adepts, on the other hand. Granting that all this is the case, though, who exactly this other character is remains a mystery that is open to speculation (the main theory holds that he is an adult Garet just as the blond adult is speculated to be Isaac), and so is whatever is the reason why Tyrell himself is not present in the party at that point in the game's story.