The remainder of this article contains lore created collaboratively by the Blaseball community.
Helga, sometimes referred to as "the Helgas," is one person who has two bodies, who for years lived apparently separate lives as Helga Burton and Helga Moreno. After both bodies wound up as batters for the San Francisco Lovers, various rumors of an apparent connection between them sprang up. In one version, Burton and Moreno were actually one woman who changed her appearance to masquerade as two separate women.
The truth was eventually revealed by the Sclience Facts twitter account just before season 4. Although Helga is now public about her true nature, she still carries on many aspects of her life attached to one or the other identity exclusively with that body. For example, Helga's blaseball stats are still tracked separately for the two different bodies.
Helga's two bodies have never been in the same place at the same time, but this is purely a coincidence.
Helga's two bodies are co-equal; neither is the "real" Helga, and neither body controls the other. Rather, one intelligence exists between the two bodies, which are telepathically linked in a way that is instantaneous even across long distances.
After Don Mitchell started experiencing periodic doubling from Reverb, it has been theorized that Helga at one point had one body, and experienced an extreme version of Reverberation.
For many years, Helga maintained a close friendship with Parker Meng through the Moreno body while trying to initiate a romantic relationship with her through the Burton body (which Parker had expressed an interest in). Parker finally confessed her feelings to Burton during the Lovers' road trip during the Siesta prior to season 4, and briefly considered herself in a relationship with Burton and a friendship with Moreno before Helga's real nature was revealed. Although initially shocked, after talking things through Parker continued in a romantic relationship with Helga.
When Mirror Parker appeared from the Tough Love dimension, she quickly initiated her own romantic relationship with Helga.