Legendary Defender:
Sven Holgersson is Takashi Shirogane's Alternate Reality counterpart and a member of the Guns of Gamara; a rebel group fighting the villainous Altean Empire. He is partnered with the Alternate Reality incarnation of Slav to infiltrate the Altean Tel-Avis deep-space shuttle and assess the condition of the Trans-reality Comet, as well as prevent it's acquisition by the Altean overlords.
As Shiro's counterpart, Sven is similar to Shiro in several respects. He's selfless and compassionate; taking a bullet for Lance without thinking about his own safety. He works well with others and trusts easily. He is also a charismatic and persuasive speaker, as he's able to convince Allura that the Alteans of his reality are really evil and untrustworthy.
Unlike his counterpart, Sven cooperates with Slav; a person Shiro finds endlessly frustrating, and he seems to lack Shiro's brilliant tactical mind. Sven prefers to oppose the tyrannical regime of his reality through subterfuge, rather than fighting them in a giant mechanical robot, as is Shiro's preference. He also speaks with a heavy Scandinavian accent, despite maintaining his Japanese appearance.
Little of Sven's personality is seen, but he appears to be heroic and brave, fighting for the good of the universe and seeking to keep the Trans-reality Comet out of the hands of the Altean Empire. Although dutifully following the leadership of his reality's Slav, he readily puts himself in harm's way to protect his allies, which leaves him heavily injured after shielding Lance from an attack. This moment shows Sven has a lighthearted and joking nature to him when he insists he is fine and simply needs to be taken to "Space Hospital".
Defender of the Universe:
Sven was part of the scout team, under Keith's command, sent by the Galaxy Alliance to planet Arus. He and the others had witnessed a massive bombardment by Planet Doom, and he was captured along with the others.
After escaping from Planet Doom, he and the others made contact with Princess Allura and Coran in the Castle of Lions. He was assigned to be the pilot of Blue Lion.
Sometime later, he had rescued Lance from an attack by Haggar, and ended up seriously injured. Eventually, he was transferred to a hospital on another planet. But Doom attacked that planet, and Sven was captured and taken as a slave to Planet Doom.
He later reunited with the Voltron Force when he helped Romelle escape from Planet Doom. Sometime after his escape, he joined Romelle instead of flying Blue Lion (control of which passed to Princess Allura) or otherwise serving the Voltron Force in a reserve capacity.
He was later part of an advance force, led by Romelle, to conduct operations on Planet Doom prior to the invasion. He was once again seriously injured after a confrontation with Prince Lotor.
Afterward, on a few occasions he would help the Voltron Force in foiling Zarkon's attempt to fill in the power vacuum left behind with the destruction of Planet Doom and its Drule Empire, and even flew Blue Lion again during an attack on Galaxy Garrison by Lotor.
Voltron Force:
Five years after the events of DOTU, it was discovered Sven was infected when Haggar's cat had attacked him and eventually the infection progressed to the point that he needed to stay in a very cold environment to keep it from overtaking his mind. He had married and had a son with Romelle, born about a year prior to the events of Voltron Force series, and probably at least conceived before Sven's infection forced him to move to a cold environment. Apparently his son had been infected as well.
He made a deal with Maahox to get a cure for him and his son. He stole Blue Lion and brought it to Crydor. Maahox betrayed him and took his son, hoping to train the boy to pilot Blue Lion for the Drules. Sven escaped and later assisted in the rescue of his son and Princess Allura. Afterwards, he defeated King Lotor in single combat and stayed on the planet...for now.
