When I started of as a junior developer it was in a team of 3. 2 Senior developers and me.
One of them was really kind and a nice guy that was getting along with everyone else in the office (other teams etc). Also he was a very good dev. Nice personal projects, knew what he was talking about, humble and hardworking.
The other developer was aweful. He was slacking a lot, all day on facebook and doing his personal home-owned business over his actual work, not caring to help me at all on any request. We didn't get along, and at first I thought it was my own issue. Later on I realized and having a talk with my manager that noone really was getting along with him.
At some point he thought it was a great idea to make an education session, I was like ok he is putting time into it. He then proceedeed telling me that he is gonna teach me the very basics of programming as "we" didnt go to uni, I told him I went to uni and I finished with a Distinction but sure he could tell me whatever. He was trying to teach me things he didnt even understand and I was taught about them at uni.
(I understand this is a basic mistake junior devs make think that they know it all, this wasn't the case here, he was trying to teach me some basic CS concepts, I went to uni for it he never went to Uni for it, he was just a programmer, nor he had the interest or hobby to go more intellectual on the matter)
This lead me into not trusting him at all, in anything, while the other developer was really kind and he let me on his own to understand that he was a really good developer and I should listen to him.
A year later my performance was really good in the yes of the company, I was producing a lot of stuff etc. The developer that didn't like me was clearly angry at me. He was producing things that could be done in a week in like 3 months. Well long story sort, the company wanted to fire him, although it wasn't very viable at that moment as they would have to pay him cause he was with them for a very long time, so they started a formal process against him by keeping schedule giving him a formal warning etc. He improved etc.
I stayed at the company till I became a developer and a year after. I was working alone on mobile apps, and I remember having a chat about an issue I had for the app and some ios apis and how I tackled it and I remember that dev still trying to tell me what to do and how although he never ever working in a mobile app in his life or any experience in that field whatsoever.
Anyways, please don't be like the 2nd developer, be nice and let junior developers believe in you and understand your actual skills and capacity on their own. You don't need to brag or try to showoff because you might end up making them not trusting you.