public with sharing class ScheduledEventMergeController {

public Intake__c thisIntake {get;set;}
public Event thisEvent {get;set;}
public Account thisAccount {get;set;}
public Id relatedAccountId {get;set;}
public Id relatedIntakeId {get;set;}
public Id relatedEventId {
    get {
        return relatedEventId;
    }
    set {
        relatedEventId = value;
        thisEvent = queryEvent('Investigation_Sched_Investigator_Email_N');

        Id relatedIntakeId = thisEvent.WhatId;
        thisIntake = queryIntake('Investigation_Sched_Investigator_Email_N');

        // relatedAccountId = thisIntake.Client__c;
        // thisAccount = queryPerson('Investigation_Sched_Investigator_Email_N');
    }
}

public ScheduledEventMergeController() {

}

public static List<FieldSetMember> readFieldSet(String fieldSetName, String ObjectName) {
     Map<String, Schema.SObjectType> GlobalDescribeMap = Schema.getGlobalDescribe();
     Schema.SObjectType SObjectTypeObj = GlobalDescribeMap.get(ObjectName);
     Schema.DescribeSObjectResult DescribeSObjectResultObj = SObjectTypeObj.getDescribe();
     Schema.FieldSet fieldSetObj = DescribeSObjectResultObj.FieldSets.getMap().get(fieldSetName);
     return fieldSetObj.getFields();
}

public Event queryEvent(String eventFieldSetName) {
    List<FieldSetMember> fieldSetMemberList = readFieldSet(eventFieldSetName, 'Event');

    String query = 'SELECT ';
    for(Schema.FieldSetMember f : fieldSetMemberList) {
        query += f.getFieldPath() + ', ';
    }
    query += 'Id, WhatId from Event WHERE Id = ''+relatedEventId+'' LIMIT 1';
    try {
        List<Event> dummyEvent = Database.query(query);
        return dummyEvent[0];
    } catch (Exception e) {
        return null;
    }
}

public Intake__c queryIntake(String intakeFieldSetName) {
     List<FieldSetMember> fieldSetMemberList = readFieldSet(intakeFieldSetName, 'Intake__c');

     String query = 'SELECT ';
     for(Schema.FieldSetMember f : fieldSetMemberList) {
         query += f.getFieldPath() + ', ';
     }
     query += 'Id, client__c from Intake__c WHERE Id = ''+relatedIntakeId+'' LIMIT 1';
     try {
         List<Intake__c> dummyIntake = Database.query(query);
         return dummyIntake[0];
     } catch (Exception e) {
         //error
         return null;
     }
}

public Account queryPerson(String accountFieldSetName) {
    List<FieldSetMember> fieldSetMemberList = readFieldSet(accountFieldSetName, 'Account');

    String query = 'SELECT ';
    for(Schema.FieldSetMember f : fieldSetMemberList) {
        query += f.getFieldPath() + ', ';
    }
    query += 'Id from Account WHERE Id = ''+relatedAccountId+''';
    try {
        List<Account> dummyAccount = Database.query(query);
        return dummyAccount[0];
    } catch (Exception e) {
        // System.addError('There is error while Fetching existing Account using Dynamic SOQL in Field Set. Error Detail - '+e.getMessage());
        return null;
    }

}}

<apex:component controller="ScheduledEventMergeController" access="global">
<apex:attribute name="theEvent" type="Id" description="the event id" assignTo="{!relatedEventId}" />


<style type="text/css">
.FS-table  {border-collapse:collapse;border-spacing:0;}
.FS-table td{font-family:Arial, sans-serif;font-size:14px;padding:10px 5px;border-style:solid;border-width:1px;overflow:hidden;word-break:normal;}
</style>

<table class="FS-table">
    <apex:repeat value="{!$ObjectType.Event.FieldSets.Investigation_Sched_Investigator_Email_N}" var="fEvent">
    <tr>
        <td>
            <apex:outputText styleClass="bold" value="{!$ObjectType.Event.Fields[fEvent].label}" />
        </td>
        <td>
            <apex:outputField value="{!thisEvent[fEvent.fieldPath]}" />
        </td>
    </tr>
    </apex:repeat>
</table>
<br/>
<h1><strong>Intake Details</strong></h1>
<table class="FS-table">
    <apex:repeat value="{!$ObjectType.Intake__c.FieldSets.Investigation_Sched_Investigator_Email_N}" var="f">
    <tr>
        <td>
            <apex:outputText styleClass="bold" value="{!$ObjectType.Intake__c.Fields[f].label}" />
        </td>
        <td>
            <apex:outputField value="{!thisIntake[f.fieldPath]}" />
        </td>
    </tr>
    </apex:repeat>
</table>
<!-- <br/>
<h1><strong>Client Details</strong></h1>
<table class="FS-table">
    <apex:repeat value="{!$ObjectType.Account.FieldSets.Investigation_Sched_Investigator_Email_N}" var="fAccount">
    <tr>
        <td>
            <apex:outputText styleClass="bold" value="{!$ObjectType.Account.Fields[fAccount].label}" />
        </td>
        <td>
            <apex:outputField value="{!thisAccount[fAccount.fieldPath]}" />
        </td>
    </tr>
    </apex:repeat>
</table> -->

<messaging:emailTemplate subject="New Scheduled Investigation" recipientType="User" relatedToType="Event">
<messaging:htmlEmailBody >
<html>
<body>
    <p>You have been scheduled for the following Investigation:</p>
    <c:ScheduledEventMergeComponent theEvent="{!relatedTo.Id}"/>
    <br/><br/>
</body>
</html>
</messaging:htmlEmailBody>

12:59:23:126 USER_DEBUG [21]|DEBUG|Intake__c:{Intake_Name__c=James test-Automobile Accident-5/4/2016, Case_Type__c=Automobile Accident, Marketing_Source__c=-com-INTERNET, What_was_the_date_of_the_incident__c=2016-05-04 00:00:00, City_of_incident__c=Orlando, State_of_incident__c=FL, Id=a00q0000008BBYUAA4, Client__c=001q000000RjkzfAAB, RecordTypeId=012q00000000cRiAAI}