As many Japanese learners already know, the particle ので is mainly used to indicate that the preceding sentence/clause should be understood as a reason that justifies or answers another statement (the best equivalents in meaning in English would probably be "because" and "since"). So, in this usage, ので is perfectly interchangeable with から, only differing in politeness level.
However, as I've seen in many sources (like here: Function of から in this conversation), から can also be used in casual speech as a sentence-ending particle that reinforces what it has been said and gives out an assertive tone (if I were to choose an equivalent in English for this meaning, I would probably say an "I tell ya" tag). So, the thing is, could ので be interchangeable with から in this usage too?
Let me show you an example of a situation where this may be possible. This is a troublesome dialogue I found while reading manga: (to put you in context, two waitresses talk about a possible new recruit and a male coworker barges in):
Adult waitress: 同{どう}級{きゅう}生{せい}入{はい}ったら楽{たの}しいかもよ？
Young waitress: 友{とも}達{だち}作{づく}りで来{き}ている訳{わけ}じゃないので
Young waiter: みてぇなつらら女{おんな} // 誰{だれ}も友{とも}達{だち}になりたかねーよ！
I'm going to write down here my personal interpretation of each line so you could better understand my doubts and why I ended up making that question about ので.
Let's begin: No problems with the first sentence except for that question mark right after the よ particle. I would never have expected the よ particle to appear in a question given its assertive tone, so I got confused and searched for similar cases. This is the only thing I found: How do I interpret this question that ends with よ?. And from what I understood, よ? exposes info, but in a "just so you know" manner (kinda like a "keep it in mind" tag). Consequently, I would translate the adult waitress's line as:
同{どう}級{きゅう}生{せい}入{はい}ったら楽{たの}しいかもよ？
Things might be fun when a classmate joins (to your job), keep it in mind.
Next is that dreaded line ending in a ので that I don't really understand. Following the "normal" use of ので (having the same meaning as the conjunction "because" in English), the line's translation would be:
友{とも}達{だち}作{づく}りで来{き}ている訳{わけ}じゃないので
Because it's not like I'm coming here to make friends.
However, that feels out of place to me. If the "it's not like I come..." clause should be understood as a reason, which other statement is being justified/answered? If the young waitress would have said いいえ before, or kept on talking, it would all make sense... but the dialogue is just as I wrote, nothing was omitted.
I struggled hard to find a meaning, but I got no satisfactory results. Then I remembered the similitude between ので and から, and I thought to myself "maybe ので works here as an informal emphatic particle like から". So I came up with this translation attempt:
友{とも}達{だち}作{づく}りで来{き}ている訳{わけ}じゃないので
There is no way I'm coming here to make friends, I tell you.
(Notice that given the hypothetical emphatic tone of ので here, I decided to level up the toughness of the 訳じゃない expression in its translation)
Aaaand finally, the waiter's line. I included this just to show that the young waitress's line has no continuation. But since we're here, I'm going to give it a try anyway (this originally came in two different speech bubbles, hence the slashes):
みてぇなつらら女{おんな} // 誰{だれ}も友{とも}達{だち}になりたかねーよ！
Look, ice-girl, nobody wants to make friends (with you)!
If anything, I have a minor doubt regarding if he meant "make friends with the girl" or "make friends in general". It would be great if you could give me your opinions on this thing too.
And that's all! Sorry for the wall of text. I hope somebody can shed some light on this question!
