If a Dragon obtained a feat that gave them a additional breath weapon is it still under the same rules as their normal breath weapon?

[Mako Senako]

Like if a dragon took eldritch heritage draconic and eventually got the breath weapon of another dragon, would they have to wait 1d4 rounds before using it again?

[Weirdo]

If they get a breath weapon from a different source, they follow the rules for that source.

The breath weapon from the draconic bloodline, for example, doesn't have a recharge time, but it does have a uses/day limit.

[Java Man]

So this dragon has mystic powers unlike other dragons, derived from the fact that, unlike normal dragons, this one has dragonblood in its lineage.

I know RAW is fine, but the ridiculous factor on that is massive.

[Pizza Lord]

Like Weirdo said, you follow the rules for that source. In the case that they aren't detailed otherwise, you follow the normal rules. For instance, if you gained a channel power in addition to a cleric's normal channel, that wouldn't change how many channel attempts you could make it a round (unless it specifically said so.) His example of the bloodline breath weapon not having a cool-down but instead a limit is correct.

Java Man wrote:

So this dragon has mystic powers unlike other dragons, derived from the fact that, unlike normal dragons, this one has dragonblood in its lineage.

I know RAW is fine, but the ridiculous factor on that is massive.

I think it's more accurate to say that this [red, blue, silver, etc.] dragon has the blood or ancestry of a different type of dragon, which accounts for why the OP said a different dragon's breath weapon. Though they would only have access to it in a limited manner and it would take a lot more time to develop and manifest in an appreciable way. I think viewing it in that context probably helps. It's not inconceivable that two dragons of differing types might mate (obviously a good and evil pairing would be highly unusual, but a tryst between two good or two evil creatures is a common trope, at least.) The game is quite open and offers many options for races and creatures to gain traits or abilities based on an 'ancestral' heritage that doesn't necessarily change their base race, but does make them unique or notably different than a baseline specimen.

[Darksol the Painbringer]

Java Man wrote:

So this dragon has mystic powers unlike other dragons, derived from the fact that, unlike normal dragons, this one has dragonblood in its lineage.

I know RAW is fine, but the ridiculous factor on that is massive.

Not really. A dragon descended from other dragons would, of course, have dragon blood in his lineage. There's no denying that it's extremely meta, but it's not really ridiculous when you factor in the most basic of genetics.

[Weirdo]

I agree with Pizza Lord that it works to represent a mixed-heritage dragon - though unless the mixing was several generations old, and therefore dilute, I'd rather make a custom dragon for that situation.