Now we have a Water card flanked by Water and Fire. The influence of the outer cards is not very strong for they weaken each other. The water card in the middle isn't all too happy yet gets at least a little support from the other Water card.
From the three, Fire is weakest.

But what if the middle card happens to be a court card - here the Knight of Cups which is Fire in Water?

While it still is valid that the outer cards weaken each other the Knight will still feel the weakened Fire of the neighbor, taking this as a however faint support for himself, adding to the already inherent instability of his character.

What this could mean gets a bit clearer when we enhance the influence of the Fire. While poor Water gets vaporized by too much Fire, the Knight turns into Psycho-Daddy.

His emotion is too much, too fuzzy, too hot, lacking every depth thus remaining superficial, almost hysterical. He has lost touch with his roots since the Water he belongs to is badly effected by the two Fire cards.

In a bold attempt to save the poor Knight we send Air to the rescue...

... with dubious results. Air is on good terms with Fire and while it does support the plagued Water a bit it also adds further activity to Psycho-Daddy, much to the displeasure of Water.

Earth might be a better choice here, bringing some much needed stability into the mix. Passive as the Water itself Earth will also take care that the stirred up mess can calm down.
Water still feels a bit bothered by the Fire aside but gets good support from the stable Earth. And best of all, the Knight can sober up from his mania.

Now Water is happy that it finally got rid of the unappreciated Fire card. Only the two modifiers - Earth and Air - are not too fond of their pairing and weaken each other. Water doesn't mind, it takes what it can get from both of them.
The Knight is also pleased, getting stabilty from Earth and active support from Air. While the influence might be weakened it is still better than nothing.

And what would be if the modifiers were both Water?

Water of course might be satisfied (to the point of satiety) - all placidity, passivity, no trouble whatsoever, nothing but blissful drowse.

The Knight, however, will see his Fire and his spirit extinguished.