|Name|| Theopholous "Theo" DuMedd|
|Occupation|| Student, storyteller|
|Residence|| formerly Castle Wulfenbach; currently Mechanicsburg|
|First Appearance|| |
|Parents|| Serpentina Mongfish (mother)|
|Relatives||Agatha Heterodyne, Zola Malfeazium (first cousins), Lucrezia Mongfish-Heterodyne (aunt), Demonica Mongfish (aunt), Lucifer Mongfish (grandfather)|
- "Pretty good. I've never heard that one before."
- "I just made it up. You liked it? My favorites are the ones with the Heterodyne boys' dopey monsters—Punch and Judy."
- Agatha and Theo 
Theopholous duMedd [pronounced doo-MEDD], or simply Theo, was formerly Head Boy among the Castle Wulfenbach students, and is a known Spark. He is well-liked, apparently for good reason, as he is a gifted storyteller and a genuinely nice guy.
When Agatha Clay winds up at the bottom of the social heap in the castle's school, Theo takes her part, just as he with a social nobody named Gil. Theo may have had a thing for Zulenna Luzhakna. It is Theo who leads the student expedition into the Baron's labs to peek at the hive engine, after which he is assigned grease trap cleaning duty of indefinite duration. When he is caught using that time to build a machine to do it for him, an unwise Lackya the Baron—in a lab where the Baron is about to cut into Othar Tryggvassen's brain, an image duMedd does not appreciate.
After Mongfish scion .A couple of months later, Theo resurfaces Agatha's escape, Theo again encounters Othar and apparently lays on him—one that features Agatha's family connection to the heroic Heterodyne Boys and what a big fan Theo is of Othar's exploits, but seems to overlook the fact that the  in Mechanicsburg, arm in proverbial arm with Sleipnir O'Hara. Their lingering distrust of Gil is resolved after they overhear him declare his intentions to help Agatha. Using the Heterodyne Device, Theo and Sleipnir rescue Gil from Vole's attempt to nab him.. With Zeetha, they accompany Gil into Castle Heterodyne and form part of his "pirate crew" for a short time, but wandering the castle .
He is was briefly her sister. Uh oh.by his aunt in Agatha's body, who has expressed that she was never very fond of
He and Sleipnir have completed transferring Von Pinn to the devil dog. The danger involved tested their relationship and demonstrated how deeply each cares for the other. Theo's own parents died twelve years ago while fighting air pirates.
Theo is currently recuperating at Mamma Gkika's along with Sleipner; who by the way was particularly when she realized that it was a brothel and not "just a beer house," before being knocked out by the ringing of the Doom Bell.
Outside world Edit
Professor Kaja Foglio has said that Theo's name was a joke based on his initial fate as a casualty during the exodus from Castle Wulfenbach, but that they grew so fond of him that his life was spared. Apparently some one is now watching out for him, or Othar might have shot the little Spark back in .
- ↑ Discussing the Dragon King of Mars
- ↑ "It family lineage, sparkiness, and some other nonsense.
- ↑ Theo the revelation of Gil's parentage pretty hard.
- ↑ Sleipnir where the Eye of the Snake Eater is hidden."
- ↑ Sleipnir will herself.
- ↑ "You the Gil we used to know."
- ↑ are we escaping?!"
- ↑ Agatha H. novel p115
- ↑ i.e. DOOMED! See Kaja's LJ