Born with cystic fibrosis, Elina was often hospitalized for costly treatment programs, the mounting bills eventually driving her father to retire from Finland's Utti Jaeger forces and take work as a freelance mercenary. However, this career change failed to solve the financial difficulties, and only caused her parent's marriage to disintegrate, and Juhani's debt grew deeper.
Sometime in 2010, Abstergo Industries' Dr. Warren Vidic led a strike team into the Berg home, alarming Juhani and startling Elina from her sleep. Juhani watched as Vidic calmed Elina and administered a medication which he claimed would cure her ailment.
Promising financial compensation and more of the medicine for Juhani's participation in the Animi Training Program, Vidic was able to convince Berg to join him, on the condition that Juhani be allowed to kill the soldier who had awoken his daughter. By 2012, Elina's condition had improved remarkably. Her father's work, however, put her in slight danger; his superiors felt that she could be a risk to Otso Berg's effectiveness as a field agent. In one case in Cairo, Egypt on 12 December 2012, Otso Berg was ordered to capture the Assassin leader William Miles as soon Miles exited his flight, but Otso Berg refrained from moving in on him until later due to the presence of a large group of schoolgirls who Miles posed as a tour guide for. When this was pointed out in the debriefing the next day, Laetitia England made a not-so subtle threat towards Elina, much to her father's anger.
Despite his relocation to Canada, Berg stayed in contact with his daughter through phone calls, keeping an eye on her education and often conflicting with Helmi due to his harshness towards Elina. He insisted that they speak English during their conversations, telling his daughter that language was power, and also berated her when she showed weakness, as for Berg her treated disease was no longer an excuse for failure. Despite his behavior, Berg loved his daughter, but for him the world was a harsh place and Elina would not be a little girl forever. As a Templar, Berg believed that he was fighting for a better future, Elina being one of his main motivation for this fight, especially after witnessing the memories of Ratonhnhaké:ton and his daughter.
In late 2018, Berg led Sigma Team in an assult on the Great Seal to Atlantis. There, Templar-turnout Layla Hassan tried to tell Berg that the Staff of Hermes Trismegistus could help Elina but he angrily cut her off for even daring to speak his daughter's name.
- Assassin's Creed: Rogue (mentioned only)
- Assassin's Creed: Reflections (picture only)
- Assassin's Creed: Uprising (mentioned only)
- Assassin's Creed: Odyssey – The Fate of Atlantis: Judgment of Atlantis (mentioned only)