Meaning of くる in 鼻の奥まで染みこんでくる

Question

独特の臭いだな。鼻の奥まで染みこんでくるぞ。

穴から水が溢れてくる

水槽に手を入れると舐め回してくる人なつっこいホトケドジョウ

てくる is something I've never really seen a clear and comprehensive explanation of the different uses and what they mean. They all just focus on the difference between the meanings and not going into depth about them.

Taking http://dictionary.goo.ne.jp/jn/64270/meaning/m1u/%E3%81%8F%E3%82%8B/ definitions

1) 少しずつ移行したり、程度が進んだりして、しだいにその状態になる
Indicates gradual change
e.g. 最近太ってきた

2) ある動作・状態が前から続いている
A certain action or situation has continued from the past
e.g. 俺はこの国を守ってきた

3) ある動作をしてもとに戻る。…しに行って帰る
To do something and return
e.g. ちょっとビール買ってくる

4) ある動作・状態をそのまま続けながら、こちらへ近づく
To describe a motion coming towards the speaker.
e.g. 先生が歩いてくる

In the examples above what 'meaning' does くる represent?

Answer 1

Please read this question first: Difference between -ていく and -てくる

Particularly, Flaw's answer there is the most relevant. Your example sentences all correspond to the definition 「4) こちらへ近づく」, but note that this 近づく does not always refer to the physical movement of something. Very frequently, this くる is used when something is moving toward the speaker psychologically.

In your examples, we can probably say the 臭い and the 水 are actually coming to the speaker physically, but the more important implication is "the 臭い/水 is going to involve me." In the ホトケドジョウ's example, its physical movement is not necessarily important, but "the ホトケドジョウ is going to interact with me" is the important nuance of that くる.

To take another example, 友達が私に話しかけて来た is a common expression, and this can be used even when the friend had been next to the speaker for an hour. On the other hand, 友達が私に話しかけた would usually sound unnatural because it sounds as if the speaker were impersonally describing someone else's affairs.