Dionne Tyrol

Dionne is the half-human/half-Cylon hybrid daughter of Galen Tyrol and Sharon "Boomer" Valerii. She solely existed in the projection created and utilized by Boomer, and was originally made at a time when Boomer and Galen both thought themselves to be human, were in a relationship and planning to settle down, and Boomer wished to have some form of child with Galen. In reality, Dionne does not physically exist, as Galen and Boomer's relationship broke down.

When Boomer came to The Fleet and was subsequently imprisoned in Galactica's brig, she showed Galen the projection of the house on Picon, and Galen was only truely taken in by the illusion when he saw Dionne's image. In reality, Boomer had used the projection to manipulate and gain Galen's trust as part of her mission to kidnap Hera Agathon.

When Galen was informed of Boomer's duplicity shortly after her departure, he was reduced to a state of denial and (apparently) went back into the projection on his own to find out if it was true. He breaks down when he finds no trace of either Boomer or Dionne (Someone to Watch Over Me).

Notes

• If Dionne had existed; then she would have been, biologically, Hera Agathon's half-sister (as both Athena and Boomer are genetically identical).