Haddon sits next to 4 phonetic neighbors — Hudson, Hadley, and Hayden are the closest matches by sound. Most share Haddon's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"heather hill, heath valley"
"God has helped"
"swift, quick"
"sickness; weakness"
"God is gracious"
"bearer of Christ"
"miracle of God"
"baker"
"wolf power, strong guardian"
"power of the homeland"
"ease, wealth"
"friend, ally"
"God has given, gift of God"
"indivisible, uncuttable"
"morning glory, morning well (depending on kanji)"
"evergreen juniper tree"
"from the Leyden region"
"powerful, excellent, good feeling"
"God is gracious"
"knife maker"
Similar sound: These names share phonetic patterns with Haddon — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Old English origins, giving them the same cultural heritage as Haddon.
Rhythm: Haddon is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.