If a character had levels in both Sorcerer and Cleric, and had the Twinned Spell Metamagic ability and the Death domain Reaper ability, would they be able to use twinned spell if one of their intended targets was within 5' of another creature who was not an intended target?
I believe this is a different question from Can I twin cast a cantrip used with reaper from the death domain? and Can the sorcerer's Twinned Spell metamagic and the Enchantment wizard's Split Enchantment feature be used at the same time? as it is not asking about targeting 3 or more creatures, I am asking if Twinned Spell can be used to target two creatures more than 5' away from each other if there is a third creature that the Reaper ability could target even though the caster does not want to.
Twinned Spell When you cast a spell that targets only one creature and doesn’t have a range of self, you can spend a number of sorcery points equal to the spell’s level to target a second creature in range with the same spell (1 sorcery point if the spell is a cantrip). (PHB p.102)
Reaper At 1st level, you learn one necromancy cantrip of your choice from any spell list. When you cast a necromancy cantrip that normally targets only one creature, the spell can instead target two creatures within range and within 5 feet of each other. (DMP p.96)
Take the situation below, where CS is the cleric/sorcerer, dashes are empty squares, and T1 to T3 are potential targets.
CS - - - - T1 T2 - - T3
The Cleric wants to target T1 and T3 with a Twinned Chill Touch cantrip. Does the existence of T2 5' away from T1 and the Cleric's Reaper ability preclude this use of Twinned Spell, as the Reaper ability modifies the spell so "the spell can instead target two creatures within range and within 5 feet of each other"?
Does the fact that it can target two creatures because of the Reaper ability mean that twinned spell will not work?
Additional points of interest: Is the Reaper ability "always on"? Can the character choose not to use it, as the Reaper description uses the word "can" which might be read to imply choice?
Finally a further note about the intent of the question: it is about whether in this specific case having the Reaper ability is actually detrimental to the character, limiting their use of the Twinned Spell metamagic ability, not about trying to use both at the same time, which has already been discussed elsewhere as noted above.