Siar sits next to 4 phonetic neighbors — Sheer, Ciar, and Seer are the closest matches by sound. Most share Siar's Irish-rooted cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"westward, to the west"
"from the fort (place name origin)"
"raven warrior"
"son of Copen (geographic surname)"
"chief, ruler"
"son of Roderick"
"little red one"
"dove"
"dark-haired chieftain"
"warrior, military companion"
"slender, narrow (from Irish Caolan)"
"gentle birth, beloved"
"descendant of Rian"
"son of Alexander (defender of men)"
"fair warrior, fair hero"
"descendant of the dark challenger"
"from Renton, town name"
"from the Afton river"
"invented modern name"
Similar sound: These names share phonetic patterns with Siar — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Irish Gaelic origins, giving them the same cultural heritage as Siar.
Rhythm: Siar is a 1-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.