Canonically the DLC takes place before any of the endings, so there are no unique interactions for Carlo.

Even in the base game, Stalkers will still recognize you as a puppet despite being a real boy.

Originally posted by corvo:

any difference if we play the DLC after the ending where we give the heart to Gepetto?

Well the whole thing is, you *arent* carlo.
In that ending, whatever "comes back" isnt Carlo.
We KNOW Carlo, Carlo was the King of the Puppets, a kind person.
Would a Kind person just kill his best friend's friends with a smile on his face?

Theres Loreheads that went into this in depth.

Originally posted by 0b:

Originally posted by corvo:

any difference if we play the DLC after the ending where we give the heart to Gepetto?

Well the whole thing is, you *arent* carlo.
In that ending, whatever "comes back" isnt Carlo.
We KNOW Carlo, Carlo was the King of the Puppets, a kind person.
Would a Kind person just kill his best friend's friends with a smile on his face?

Theres Loreheads that went into this in depth.

Romeo is the king of puppets not Carlo they are two different people

Originally posted by 0b:

Originally posted by corvo:

any difference if we play the DLC after the ending where we give the heart to Gepetto?

Well the whole thing is, you *arent* carlo.
In that ending, whatever "comes back" isnt Carlo.
We KNOW Carlo, Carlo was the King of the Puppets, a kind person.
Would a Kind person just kill his best friend's friends with a smile on his face?

Theres Loreheads that went into this in depth.

Dunno where you got this info as this is wrong. King of puppets is someone else and it's mentioned in like 3 different occasions who he is.

That thing wasn't Carlo. Multiple ergo cores were in that thing INCLUDING Arlechino's which is probably a big reason for that ending going the way it did. Look at Arlechino's wiring where he's imprisoned its same stuff connected to the nameless puppet that becomes "carlo". The nameless puppet weapon makes note of this and calls that thing a resentful killer, not human.

Dlc does change some things in the main game if you do it early but I haven't noticed anything vice versa. Heck I did it after beating the game and Gemini still acts all confused and asks what the alchemists could possibly be doing when we know damned well already from beating the game. Shame no little changes in the dlc but at least the dlc has neat little things in the main game after.

The 'Carlo' in the Real Boy ending isn't Carlo, it's just a human puppet facsimile of what Gepetto wanted his son to be, judging by the unpleasant implications of the Piercing Hatred amulet and everyone getting murdered. If the good ending is about a formerly-human puppet becoming a human again with Carlo regaining his sense of self, then the bad ending is about being genuinely reduced to a puppet.

Any notes that change retrofit themselves if they were previously collected. The only thing the DLC must be done first for is Lea's changed dialogue on the ch11 memory beach, but you can avoid interacting with it, walk right past it, complete the game and DLC and then come back for it with no issue.

To be fair, Lea is already suffering from the Petrification Disease while on a su*icide mission to save her last apprentice/last living found family member from a murderous serial killer puppet with a huge grudge. She's not in the best mental state and healthy condition to consider how familiar P is to her Carlo. She barely even notices Gemini on your person during the run up to the Rose Estate.

Anyway I tried it and there's no new hidden dialogue which makes sense because like others have said, the Real Boy is not the same as the Carlo who died. He's become a living puppet of mass destruction for Geppetto himself. To her, you're basically a stalker who looks familiar until she realizes at the end regardless of being "Carlo" or not.

Carlo is dead. Like Cyberpunk and V, P is a puppet clone of Carlo with his memories. I think it isn't until he gains a soul through whatever blue fairy magic is going on does he start becoming close to what Carlo was. Unless he chooses the real boy ending and he's a soulless puppet human clone.