Leaving aside how to do this in Fabrik, from a straight technology perspective then you need to either:
a. Include the information in the web page (list) and use javascript to show it in a tooltip; or
b. Use Ajax to go and get the information from the server when the user hovers over the item. Ajax calls take several 100ms at minimum, and you probably want to wait for (say) 250ms hovering before you issue the ajax call (otherwise if the user moves the mouse briefly over each item, it will trigger a plethora of ajax calls which will potentially swamp something - so probably in excess of 1s for the information to appear.
From what you say, it sounds like the list has everything in it, but you are prefiltering it so it only shows some records, and you want to show the other records in the tooltip. If this is the case than this is good, because rather than use a prefilter, you can hide the records you don't want seen and then use JS to show the records when you hover over the corresponding one.
Without more detail it is difficult to offer Fabrik solutions, but one which comes to mind is to create an element which holds a class and in the List options for the element set "use as row class". You can use the class to select css that hides the row. Now you are half way there because all the data you need is already downloaded in the web page even though half of it is hidden.
Then you need to create JS that shows the matching row when you hover, and hides it when you leave hover.
Please post here to let us know how you get on.