This is how Willy's story goes in Thomas and Twilight Sparkle's Adventures of The Rescuers Down Under.
Bernard: Jake's been gone for a... OW! a long time... Oh! maybe I should go look.. Oh! For him
Bianca: Oh, Bernard.
Willy: Where is he? We'll never reach McLeach's hideout at this rate!
Fluttershy: Um, Willy? Are you alright?
Willy: I'm just fine.
Applejack: Ya sure about that?
Willy: Yes I am. [turns away angrily with his fins crossed]
Shining Armor: Willy, ever since we first got here; you've made it a goal to kill McLeach. Why are you so determined to do so?
Willy: Because he's a poacher.
Rainbow: What's him being a poacher have to with you wanting to kill him?
Edward: Why do you wanna kill McLeach for being a poacher?
Willy: [(is started to get fed up with all the questions thrown at him and soon he loses it.) Turns around and with his fins in the air] IT'S BECAUSE POACHERS KILLED MY FAMILY!!!!
Twilight, Rarity, Applejack, Rainbow, and Pinkie: GASP!!!
Fluttershy: Poachers killed your family?
Willy: [realizes what he just said, and knows he has no choice but to tell the truth] It's true, my family was killed by poachers.
Thomas: How come the poachers killed your family, Willy?
Willy: Finacal gain. Common thing for poachers, my breed of whale can provide nice smelling oil melted from our blubber.
Spike: How long ago?
Willy: 37 years ago, before I was an engine.
Rainbow: Wait just a minute! You mean you weren't always an engine?!
Willy: No, I was once a regular whale. So anyway, me and my pod were swimming just across the Pacific...
(In the flashback)
Willy: (narrating) My family and I weren't alone, there was at least 47 whales in the whole pod
Willy's father: Look, William. Plankton!
Willy: Father, are you sure about going that way?
Wiily's father: Oh course I am.
Willy's brother: Yeah William, let's go.
Whale 3: Yeah, let's do it.
Willy: Okay then. (All whales swim towards the plankton but before they can eat it, they swim away then a whole bunch of nets come down)
Willy's father: Holy White Squall, it's a fleet of whalers!
Willy: (narrating) It was too late to swim away. (All whales try to avoid the nets but to avail and some get harpooned and hoisted out of the water.) At that time I went into my first rage mode and swam up and attack one of the boats.
Whaler #1: Whale on deck!
(they all try to escape Willy, but he grabs one of them.)
Whaler #4: AAAHHHHHH!!! (His head is in Willy's mouth) [muffled] AAAHHH!!!! (Willy then bites down and cracks the guy's neck)
Willy: (narrating) After that whole thing was over, there were only 18 whales including me, left swimming. I knew I couldn't stick around there anymore. So I set off for Cartton World. (We are shown a montage of Willy swimming) 10 days; no food, or sleeping. When I finally reached the coast, I collapsed onto the beach and was found by some scientists. They when I woke up, I was now an engine.
(The flashback ends)
Willy: I never seen ding or wing of my pod ever again.
Percy: That's sad.
Pinkie Pie: Yeah.
Fluttershy: Oh my.
Princess Cadance: Wow. You remember your family very well.
Thomas: She's right.
Twilight Sparkle: What thing do have left to remember your family?
Willy: The only thing I have left to remeber my family is... (pulls out a golden object) this.
Rarity: A golden pedent?
Willy: It's not a pendent. (Clicks a button on the top and it opens up revealing a watch and a picture of Willy and his father.) it's a golden watch.
Twilight: (Takes the watch with her magic) Is that your father in this picture?
Willy: Yes, that watch was a gift from my father. (takes back the watch) Afterwards I gotten my fins into the M1 Garand I carry now and later my dagger and harpoon gun. I vowed to exterminate all poachers I come across to teach them to hurt innocent animals!!
Shining Armor: Calm down, Willy.
Edward: He's right.
Willy: I'm alright.
Fluttershy: [places her hoof on Willy] I'm so sorry about your family Willy, no one should go through something like that.
Willy: I know, and I wish that it never happened.
James: There's some things that can't be changed.
Pinkie: (with tears in her eyes) I can't beleive you lost your family!
Rarity: (with tears in her eyes) I can't beleive those monsters would do such a thing for money!
Willy: I know! But you guys remind me of my family, but I still miss them very much. (Starts weeping)
Fluttershy: [gently holds Willy] Don't cry. It's okay. But I can understand it.
Thomas: Look, Willy.
Twilight Sparkle: Please stop weeping.
Willy: (stops weeping but still has tears) Thanks, Thomas and Twilight. but that still doesn't change the fact that poachers hurt innocent animlas for money! So far, I've killed 70 and it'll be 71 when we get McLeach.
Fluttershy: Oh. Do you have a care about about animals?
Willy: I do have a care for animals like you do. I myself am one. [sniffs, as a tear slids down his check] Besides, my breed of whale is sadly endangered.
Apple Bloom: Wow.
Sweetie Belle: That's terrible.
Scootaloo: So that's why Willy wanted to kill Mcleach.