Lil quick note: Most of the headcanons I come up with, I think of while watching the show. I'll post what episode it was that inspired such a headcanon, in case anyone is wondering where the heck that came from. XD 

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Headcanon: Even after joining SHIELD, Peter kept his old webshooters with him for the first few months because he didn't completely trust the ones Fury gave him, and the old ones were something of a comfort object to him. That, and he wasn't ready to give up his self-made webshooters just yet, even though the SHIELD ones were made better.

Furthermore, after graduating from SHIELD Academy, Peter upgraded his originally designed shooters into smaller, compatible bracelets that he can store and use if ever his SHIELD ones fail him or are destroyed. (A lesson he learned after Otto took his powers and crushed his SHIELD web shooters). 

 Referenced from: Season 1, episode 21, "I Am Spider-Man"  

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Funny fact: In season 1, on the episode "I Am Spider-Man", when Peter has to 'go behind the scenes' to defeat Trapster using Flash at the museum, you'll notice that Peter is using his self-made webshooters, not the ones SHIELD gave him. 

Example: 

Here are two pictures from "I Am Spider-Man" when Peter is "making Flash look good" as Spider-Man, on top of/near the museum. 

And here's a closer look: 

And now here are two pictures from "Graduation Day Part 2" when Aunt May gave Peter his old webshooters as a graduation gift: 

Closer look: 

Next, Peter's SHIELD web-shooters: 

And now, side-by-side with the SHIELD webshooters cause I feel the need to rub it in! 

Those are definitely not the same webshooters. So, why would Peter be carrying around his old webshooters back in season 1 if he had the new, "cooler", SHIELD ones that go invisible, has taser-webs, and aim-guidance? 

Well, my answer, Peter didn't want to give up his old webshooters, and, I'll go as far as to say, that he didn't quite trust them yet either. He mentioned that his old webshooters jammed a lot, back in the episode "Nightmare on Christmas", so maybe he was concerned that the SHIELD ones would do the same and brought the old ones as backup. Maybe he just liked having his old ones with him. 

Or [The sinister side whispers] maybe he just had them because Flash had his suit on at the time, and the webshooters were still attached to the suit, thus he had to resort back to his old ones!

BUT - because I want to argue with myself, I will say that if the SHIELD ones were, in fact, still on Peter's suit, Flash probably would've noticed them eventually. He crossed his arms quite a lot in the episode, and the SHIELD webshooters are big and clunky, thus Flash should've been able to feel them at one point. So, I deduce that they were not there, maybe Sam took them off or something (so Flash didn't hurt himself), and Peter simply carries around his old webshooters because he trusts them and/or they're his comfort object! 

HOO-HA! 

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For those of you who have made it to the bottom of my unnecessarily long headcanon/dive into the series, congrats! I probably didn't need to go this deep into the headcanon, but it was fun, I had nothing better to do (other than to procrastinate the fanfics I need to update), and I just love needlessly explaining myself.

Thanks for sticking around till the end! :P

You are, the Ultimate Chillada's!