I keep seeing everyone throwing in the Multiclassing statement of
"With this rule, you have the option of gaining a level in a new class whenever you advance in level, instead of gaining a level in your current class. (PHB, p. 163)"
But what I am not seeing, is people seeing the ine word to break it all.
You have the OPTION to take levels in a new class.
I have recently been tasked with making a whole slew of characters for a dungeon crawl game for beginners to gain knowledge in many aspects of the game, D&D5e. And with that, have studied the book and many other guides extensively, and all I've found is methods towards making characters within one class multiple ways, AND in multiple facets towards inversion.
I would debate against the norm of answers and state that the Multiclassing feature as writ states NOTHING against Multiclassing within one's own class, given you choose a different Archtype.
Now let me explain how I had come across this.
When leveling, you still have a choice as to how you spend your exp and dole out your points. Choice.
You CAN accrue experience and when enough is saved, you do have the ability to dive Right into a secondary Archtype.
Using the Sorcerer, for ease of explanation, the Draconic Resilience and Wild surge. By law of lore and the basis of D&D(Storytelling) you can leave a tale of two lives in one.
The biggest thing is EXP needed to do such, let's dally back to a Fighter/Fighter.
Sure, your walking right back into the same low level class features of Action Surge and Second Wind.
Obviously you wouldn't be able to gain these features twice, that would go against the fighters training regime. But in that same token, your training can allow you to start as a Champion, a fighter for entertainment. Now using the Storytelling Clause, who's to say that Champion of the people doesn't decide to go into the Military, and enjoys it. A Champion being mostly akin to a Gladiator, there is some Moxy and bravado in it all, which having that intimidating demeanor, why not become a Battle Master. Barking your orders and using your flashy skills hard learned in the arena to be the basis for the Battle Masters maneuvers.
Being an avid player for almost 2 decades, this has been a fierce debate over many Players.(and I mean that totally in a nice way, but players don't run a game)
But when you ask a DM, and state the correct correlation of STORY with the precise method of acquisition towards set up, I've met none who can deny the rules as writ do Not state you're unable to facilitate levels back within your class, just with the Intelligence to know you can't take certain features twice over(unless the features state they are able to be taken multiple times)
Again, this is an opinion as credible as any other. And using the same wording from the PHB as others do. Just seeing the words they seem to overlook.