Darth Maul is Found By Ezra Bridger on Malachor

Ezra uses his lightsaber for light in the Malachor underworld while Maul looks on

While we haven’t seen what Maul does following the events in Solo: A Star Wars Story (at least as of this writing), where he was still head of Crimson Dawn, we next see him in the season 2 finale of Star Wars Rebels, “Twilight of the Apprentice”.
Ezra Bridger Accidentally Finds Maul
In the first part of “Twilight of the Apprentice”, when Ezra Bridger falls through a level after having been attacked by an inquisitor and getting spatially separated from Ahsoka Tano and Kanan Jarrus, Ezra tells them he’ll be okay, even though he doesn’t know where he is (“Sure, I’ll catch up. Soon as I figure out where I am”). To this, a hooded Maul replies to Ezra, “I know where you are. You’re with me.”
As Maul chuckles and approaches, Ezra ignites his lightsaber, to which Maul calmly implores him, “Please put your weapon away. I-I mean you no harm.”
Ezra Bridger: “Stay back! I’m warning you, old man.”

Maul Has Spent Years on Malachor

This transitions into a curious scene wherein Maul is hooded in the dark and, as we’ve never seen him before, he is moving slowly, talking slowly, and now, even apologizing: “Forgive me, it-it’s just, I’ve been alone so long. It’s been years since I’ve spoken to anyone.”
Ezra: “You live here alone? Uh, in the dark?”
Maul: “Not by choice. My ship crashed. I’m trapped, marooned. I’ve had to scrounge and scrape to survive.”
Ezra: “Look, I’m sorry. Okay? I wish I could help you, but I have to get back to my friends.”
Maul: “Well, perhaps I could help you.”
Ezra: “I doubt that.”
At this point, Ezra clearly perceives Maul as a feckless old man, which is amusing to viewers who know who Maul is, but, to Ezra, he is just an old man who happened to have crashed on Malachor.

Maul recruits Ezra to Help Him Find What They Came For
Continuing on in their introductory conversation, Maul inquires, “Why are you here?”
Ezra: “I’m not gonna tell you that.”
Maul: “You came for the same reason I did, years ago. You seek knowledge. It’s in the temple, isn’t it? And I know the secret way to get inside, but, but I’m too old. I-I-I need help to open the door.”
Ezra: “What’s inside?”
Maul: “Help me and find out.”
Ezra: “Show me this doorway.”
Maul: “Please, this way.”
Ezra: “You first.”
Maul: “Do you not trust me?”
Ezra: “I don’t know you.”
Maul: “W-Well, then let’s change that. Call me ‘Old Master’. And you?”
Ezra: “Call me ‘Jabba’.”
Maul, after a [knowing] pause: “Hmm. Come then, Jabba.”
In this stage of meeting, Maul and Ezra are not yet sharing their names, with Maul using a vague name such as Old Master and Ezra using a pseudonym of Jabba, yet Maul is sinking his hook into Ezra to get to the Sith temple. It’s also amusing that Maul seems to know that Jabba is clearly not this boy’s name and may even pick up on a certain unease of Ezra’s.

Ezra Is Concerned Maul is a Sith
While walking amidst this subterranean area of Malachor, Ezra asks Maul about their perambulating: “How much further?”
Maul: “You worry about your friends?:
Ezra: “They need my help.”
Maul: “Yes, (SIGHS) and with good reason. The Inquisitor is powerful.”
Ezra: “Wait, you know about the Inquisitor?”
Maul: “He is my enemy. All Inquisitors and their masters are my enemies.”
Ezra: “Were you a Jedi?”
Maul: “Uh, no. No, no. But I was once a Force-wielder, long ago. Long, long ago.”
Ezra: “Then you’re a Sith?”
Maul: “The Sith – The Sith took everything from me. Ripped me from my mother’s arms, murdered my brother, used me as a weapon, and then cast me aside. Abandoned me. Once, I had power, now, I have nothing. Nothing.”
Ezra: “I know how you feel. The Empire, it took away my home, and my mother, and my father.”
Maul: “And you want revenge.”
Ezra: “I want justice!”

In this mini-interaction, Ezra suspects that Maul is a Sith, although Maul quickly denies it and then even doubles down on it, saying that he had been used by the Sith as a weapon, but had been cast aside. It’s such a fascinating formulation of Maul’s experience for Maul not to admit he was ever Sith. Of course, it’s not clear if this is exactly how Maul perceives his experience with the Sith or if it is how he wants Ezra to understand Maul’s experience with the Sith.
It is also curious to see Maul steering Ezra towards considering revenge towards the Empire, yet Ezra pushes back and tells him he wants justice, not revenge, which leans more towards the dark side.
Maul Encourages Ezra to Help Him Find What is in the Temple
Continuing in their conversation, Maul tells Ezra that he can achieve justice: “Yes, yes! And you shall have it, – for I have discovered the key.”
Ezra: “The key to what?”
Maul: “The key to destroying the Sith.”
Ezra: “Well, that is the knowledge inside the temple?”
Maul: “Yes, that temple holds secrets of the Sith, secrets that have been buried with the dead for thousands of years.”
Ezra: “And you’ll share this knowledge with me?”
Maul: “Yes. Yes, of course.”
Maul tells Ezra that he can help Ezra achieve his desires of destroying the Sith [and the Empire] if they go into the Sith temple for Sith secrets. While it is unclear at this point if Maul is being genuine in his assertion that he will share this knowledge with Ezra, it could also be that Maul is trying to recruit him.
What’s Next
In the next installment of the Darth Maul Project, we see Maul and Ezra enter the Sith temple on Malachor.