Both Uses of

relative
in
The Sea of Monsters

Chiron was among the crowd, but his relatives were almost nothing like him.†
Chpt 18

Definitions:

(1) (relative as in: the relative importance)
compared with something else (not an absolute value or not complete)
(2) (relative as in: they are relatives)
connected
in various senses, including:
- a person related by blood or marriage -- as in "The hospital won't let me visit her because I'm not a relative."
- a plant or animal related by origin or grouping -- "The closest relative of the dog is the gray wolf."
(3) (relative as in: questions relative to the topic)
related to
(4) (meaning too rare to warrant focus)
meaning too rare to warrant focus:

More specialized and less common senses of the word are found in philosophy, grammar, and music. Consult a comprehensive dictionary if you wish to see those. All senses have to do with relationships.