EDIT: And it's a landslide win for....
Sanjiv, Maddie, and Daffy (Tonks's friends)
So... coming up: fifty things about Tonks's wacky school sidekicks.
1. Sanjiv's mother is a first generation immigrant from India who went to Edinburgh to study medicine and met her husband there. He was a gardener on the grounds.
2. Dora "Maddie" (Madrigan) Apcarne is an extremely pale blue-eyed blonde, who tends toward the chubby.
3. Dafydd "Daffy" Apcarne is tall and gangly, even into adulthood, though as a teen, it was absurd. He has strawberry-blond hair and light freckles.
4. Sanjiv is homely--he has crooked teeth, a nose too big and broad for his face, and curly hair that sits like a disspirited mop on his head--but is supremely self-confident and charming, so girls who've known him for a long time are often surprised when other girls don't immediately consider him a catch.
5. Daffy does know that his name is not actually pronounced "Daffid," but once Tonks and Sanjiv got hold of the spelling, he was "Daffy" for life, and he never particularly minded it. (He'd secretly thought himself too dull for a nickname, and was pleased to get one at all.)
6. Maddie's grandfather is an American Muggle, who was stationed in England during WWII. She sometimes visits cousins in Maine, who are very curious as to why they never need to pick her up at the airport.
7. Sanjiv's Muggle grandparents still live in Bangalore, and are so proud of their Muggle-born wizard grandson that they insisted on being introduced to the local magical community just so they could have somewhere to brag about him and show the pictures he sends.
8. Daffy was a prefect from fifth year, and Head Boy in his seventh (edging out Charlie Weasley).
9. Maddie was the only one of the gang to be on the Hufflepuff Quidditch team for more than one season. She was Keeper from their fifth to seventh years. (Daffy was a Chaser seventh year; Tonks, a very bad substitute Beater during fourth year; Sanjiv, a poor flyer who never tried out.)
10. Sanjiv's ambition is to be a political cartoonist for the Daily Prophet, but since the position doesn't exist, he entertains himself by drawing scatological cartoons of the editorial staff.
11. Daffy once got two weeks' detention for "anonymously" writing an explicit story involving Snape, Trelawney, and a vial of unidentified potion.
12. He did this because Maddie was driven to tears by Snape teasing her about one of her early romances.
13. The year that Sanjiv and Tonks got their licenses to drive, Sanjiv challenged Tonks to a race from his home in Edinburgh to her home in London. Daffy rode with Sanjiv; Maddie with Tonks. Tonks won, and teased him about it for some time.
14. Daffy was the first person who knew Tonks's heart belonged to a mysterious person outside of their school circle.
15. Maddie is a horrid housekeeper and a congenital packrat, and her area of the dormitory always looked like it had been hit by a cyclone.
16. Sanjiv maintains a separate friendship with Ted Tonks, who still likes to network Muggle-borns when he can, and Sanjiv tries unsuccessfully to re-create the MUDS.
17. Daffy and Tonks went out, but they were never very clear on the concept, and sort of forgot to break up. When Daffy asked Tonks to stand up at his wedding to Maddie, she joked that they should, perhaps, break up first.
18. As an Unspeakable, Maddie works in the Time Division of the Department of Mysteries, and after the battle at the DoM, she got stuck with trying to clean up the Time Turner spill.
19. Sanjiv once tried to kiss Tonks, who rejected him as gently as she could. He now pretends it was meant as a joke, and she pretends to believe him.
20. Daffy's father is a Muggle-born wizard, and his mother is a pure-blood Squib.
21. It was Maddie who got Tonks hooked on trashy paperback romances.
22. Sanjiv works for Muggle companies as well as wizarding ones--he's a freelancer, and takes work where he can find it.
23. Daffy's job as a textbook editor is sheer drudgery, and he keeps himself entertained by inventing new charms to do the same old tasks, but with great flourishes. (Eg, a spell to find typos will explode in fireworks and spell out the mistake in the air.)
24. Maddie's family believes that she got married too young, and they are not on especially good terms because of it.
25. Sanjiv has no particular belief system of his own--his parents are both non-practicing and come from different traditions--so he feels justified in celebrating each and every holiday he hears about, if it sounds remotely entertaining. He hosted the only known Purim party in Hogwarts history in the Hufflepuff common room.
26. Daffy speaks fluent German (several historical dialects) and is translating a set of medieval spellbooks from the Black Forest.
27. Maddie habitually paints her nails with complex geometric patterns. (This habit has been broken by the necessity of handling a baby at unpredictable intervals, though Francis's blankets have long streaks of nail polish goo on them from early attempts at multitasking.)
28. Sanjiv's father made a point of taking him on trips during summer holidays where he would be exposed to great art.
29. Daffy attempted to start a dramatics club at Hogwarts, but couldn't find enough interested students to launch the production he wanted to launch.
30. At home, Maddie tends to go around barefoot, often because she can't find her comfortable shoes under piles of papers she's reading.
31. Sanjiv lost interest in driving fairly quickly and sold the car he'd bought.
32. Daffy wasn't close to his sister while they were growing up, but as adults, they've become friends.
33. Maddie had a horrendous crush on Hagrid during her third year, and is, to date, the only student who ever tried to call him "Rubeus." Stress on tried--she pronounced it "Ru-BAY-uhs."
34. Before his freelancing career started to take off, Sanjiv did various odd jobs, mostly in Hogsmeade, including doing inventory at Zonko's and waiting tables for Madam Rosmerta.
35. Daffy has an Outstanding NEWT in Care of Magical Creatures.
36. Maddie did especially well in History of Magic and Astronomy.
37. Sanjiv was the only one who came close to keeping up with Tonks in Potions. He claimed it was because his mother insisted that he study chemistry.
38. Daffy's shameful secret: he not only is a distant cousin of Celestina Warbeck's... he likes her singing!
39. Maddie is related to the Longbottom family, though I doubt she knows it in anything more than a passing way.
40. Sanjiv is a tall man with broad shoulders, but he tends to slouch.
41. Daffy's hairline started to recede during seventh year. It's not so bad that he can't hide it (except from Maddie), but he knows he'll be bald as a cueball, like his father, by the time he's forty.
42. While Maddie enjoys learning about distant places, she cordially dislikes traveling to them.
43. Sanjiv doesn't take his romances seriously at all, and because he hasn't ever brought a girl home (not counting Tonks and Maddie), his family is under the erroneous impression that he is a "confirmed bachelor." His mother keeps trying to set him up with another "confirmed bachelor" who works at her hospital.
44. Daffy had never thought about being domestic, but since his marriage, has found that he rather likes being chief cook and bottle-washer, and has a much better flair for the culinary than his wife.
45. Maddie idolized Tonks in school, but decided that trying to emulate a mercurial metamorphmagus was too difficult, and therefore simply developed her own personality instead of trying to copy Tonks's (much to the latter's relief).
46. Sanjiv likes to play the piano.
47. Sometimes when Daffy brings Francis to the office, he uses his quills as puppets and puts on a show for the baby, using his desk as a stage.
48. Maddie sometimes referred to Tonks as Yvodora, as she once observed Tonks signing a long letter "Y.V.O. Dora." Maddie immediately decided that this was the name Tonks should write bodice-rippers under: "Yvodora Nymph." Tonks made an uncomplimentary comparison between Maddie and her own mother in terms of naming choices.
49. Maddie and Daffy's son, Francis, will grow up to sit on the Wizengamot.
50. Sanjiv will not marry until relatively late, and will marry a widow whose children he will adopt. I'm not sure who, though I think she's one of the current Hogwarts girls.