Lantos was a low-level demon who worked under the employ of the Demonic Sorceress known as Imara. Imara planned to swap souls with Piper Halliwell in an attempt to gain respect, beauty, glory and power and to prevent Zankou from becoming ruler of the Underworld allowing her to take control. Lantos was her top servant and was sent to attack Piper at P3 to acquire a lock of her hair for Imara's Soul Swapping Spell. However, after a failed attempt and destruction of another servant at P3, Imara set her sights on Phoebe instead.
Imara then sent Lantos to acquire a strand of Phoebe's hair; albeit he was reluctant to proceed with the plan due to the assumption that Piper was now aware of an impending demon attack and alerted her sisters. After Imara threatened and scolded Lantos telling him she will not work for Zankou, she questioned him about whether or not he thought she was beautiful, he responded of course, with the snicker from a female servant. Lantos requested more demons to assist with the plan, Imara refused and he then questioned why not going after Paige instead but Imara was dead set on Phoebe instead.
Lantos as well as another demonic servant who worked for Imara shimmered into the elevator at The Bay Mirror as Phoebe stepped into it. With her back to the two demons, Lantos attempted to cut a strand of her hair but Phoebe fought back, kicking the other demon and then flipping over Lantos, who launched a fire ball that struck the other demon instead of Phoebe. After the demon's destruction, Lantos managed to snip a lock of Phoebe's hair and shimmered out just as Phoebe grabbed the scissors he had, which she stabbed into the elevator wall in an attempt to wound the demon.
After returning to the Imara's lair in the Underworld with the lock of hair, Lantos angrily told Imara he barely escaped and told her they should hold off on the transfer of souls because of Phoebe's heightened Intuition as well as the bond the girls share and how they be expecting another attack. Imara refused, pushed Lantos back sending him flying backwards landing on his back and she proceeded with the soul swap.
Imara placed the lock of hair in her potion and the transferred occurred. With Phoebe's soul now in Imara's body, Lantos locked her in a magically sealed cage. Phoebe demanded to be let out saying Imara won't get away with what she has done stating they will now there is a demon in the Manor. Lantos then reminds Phoebe of how Zankou was in the Manor and they didn't know about it and he tells her Imara managed to break into Zankou's lair and stole all the information he collected about the Charmed Ones and that the plan will succeed because of that information. Phoebe again says her sisters will find out what they have done, Lantos then said by the time they do, it would be too late and Zankou's allies would all be destroyed, weakening him to the point that he is unable to rule the Underworld, allowing Imara to gain control. Lantos then tells Phoebe that Imara is only keeping her alive so she can transfer back into her own body and tells her there won't be a body for Phoebe's soul to return to.
In Imara's body, Phoebe manages to trick Lantos into believing her sisters discovered the plan and that Imara has returned to her own body, demanding to be let out of the magical cage, threatening to kill Lantos and the other demon. She then says the plan failed because of the scissors he left behind. Lantos partially believes her and shimmers to the Manor to see if it is true, telling the other demons not to allow her out until he returns.
He arrives in the Attic with a fire ball in hand to Imara in Phoebe's body who tells him she is lying. She then calls to Piper for help, he asks what she is doing and she responds "covering". Piper runs to the Attic and blows Lantos up.
Lantos appeared in a total of 1 episode throughout the course of the series: