Sif, Heimdall's sister, has been Thor and Balder's constant companion since childhood.

Entity and relation annotations:
id: 0
type: entity
value: text: Heimdall
labels: <Person>
id: 1
type: entity
value: text: Thor
labels: <Person>
id: 2
type: entity
value: text: Balder
labels: <Person>
id: 3
type: entity
value: text: Sif
labels: <Person>
type: relation
to_id: 0
labels: Person:business/work:Person
from_id: 3