[Narrator] Throughout Star Trek's long history
with shapeshifters,
none are more dangerous than the Changelings,
also known as the Founders of the Dominion.
Major, the Changelings are the Dominion.
[Narrator] And in Star Trek: Picard Season 3,
the Changelings have returned
with designs on conquering the galaxy.
Your federation will crumble.
He is a Changeling.
[Narrator] In Star Trek: Deep Space Nine,
fans are first introduced to the Changelings
by way of Odo,
Security Chief on the series' titular space station.
I've been called a Changeling on occasion.
[Narrator] With no memory of his past,
Odo longs to know more about his origins.
The exploration of you, what you are, where you came from.
That's never far from your mind, is it?
That part of it is true.
[Narrator] However, he soon finds answers
when his fellow Changelings invade the Alpha Quadrant.
Calling themselves the Founders,
they start what will be known as the Dominion War.
The Changelings have reached Earth.
[Narrator] Upon their first meeting,
The Founders reveal to Odo
that the Changelings evolved on a distant planet
in the Gamma Quadrant,
where they live in their liquid form
in a large sea called the Great Link.
The Great Link tells us that many years ago,
our people roamed the stars, searching out other races,
so we could add to our knowledge of the galaxy.
But how could you be sure
that we'd find our way back here?
The urge to return home
was implanted in your genetic makeup.
[Narrator] As the Changelings explored the galaxy,
they were met with hatred and violence
at the hands of the Solids.
No!
[Narrator] For self-preservation,
the Founders formed the Dominion
to end their abuse, no matter the cost.
We will emerge stronger,
and in a far better position
to take the Alpha Quadrant once and for all.
[Narrator] Devastated, Odo refuses to join
with the Changelings
in their vengeful attacks on the Alpha Quadrant.
Nevertheless, the Dominion sees great success in the war,
through their use of shapeshifting spies
and the military prowess of the Jem'Hadar.
Thanks to their unique liquid anatomy,
Changelings do not die of natural causes,
but they are not immortal
or immune to other threats on their lives, either.
Determined to exploit their vulnerability,
and thereby eradicate the Dominion threat,
Starfleet's Section 31 tortures several Changelings
to develop a lethal virus.
Odo is infected with the virus,
and passes it on to the Founders through the Great Link.
Disgusted by section 31's genocidal intentions,
Deep Space 9's Chief Medical Officer,
Dr. Julian Bashir, develops an antidote for the illness.
Odo agrees to cure his people of the virus
in exchange for the Founders' surrender, ending the war.
Fulfilling his promise, Odo returns to the Great Link,
curing his people and building a new peaceful Dominion.
Though most of the Changelings remain in the Gamma Quadrant
as part of the Great Link,
there are some who have separated from the rest.
On Star Trek: Picard, they hide among the Solids,
sowing chaos throughout the galaxy.
[Jack] I was attacked.
His face.
It moved.
There's a Changeling on board.